Freshdesk has different kinds of ticket fields that let you capture various types and levels of information. For example, you could use single-line text fields to collect one-line information like the name of the company, and you could add drop-down fields to give your customers a list of options to choose from.  

The ticket form helps you take support queries and collect feedback from your customers. It is shown by default in your support portal. The ticket form helps you collect all the facts you need at the very first step, eliminating the need for you to go back and forth to the customer with more questions. With this in mind, you can customize your ticket form to fit your business type or your internal support process. 

Default Fields in Freshdesk:

Every Freshdesk account comes with a set of default fields that are important to the functioning of your helpdesk. These fields are a part of every ticket in your helpdesk and will be used by your agents extensively as they try to resolve issues. For this purpose, default fields cannot be removed from your ticket form. However, you can control the way they are visible to your customers in your support portal.

Default fields
What they mean
Requester
A new account will be created in your Freshdesk portal when a new user creates a ticket. It is a mandatory field for both your agents as well as customers when they submit a ticket. This field will be filled in automatically for a logged-in user.
Subject
Ticket subject helps you get quick context. A proper subject line will help you set up intuitive automation.
Type
Helps categorize the ticket according to the different kinds of issues your support team deals with. The values of the type field can be edited by clicking on the field.
Status
Shows the current status of the ticket. The default statuses cannot be changed. However, you can edit the name of the statuses that are seen by the customer.
Priority
Shows whether the ticket is an Urgent, High, Medium or Low priority ticket. You can control what each priority means in Admin > SLA Policies. 
Group
Agent group that the ticket is assigned to. To edit the values of the group field, go to Admin > Groups.
Agent
The agent is currently assigned and working on the ticket.
Description
A detailed description of the ticket.

Different Type of  Custom Ticket Fields:

Custom field type
Example use-cases
Single line text
Customer name, company name.
Multiline text
Additional descriptions, addresses, notes.
Checkbox
Subscriptions, Agreements.
Number
Order ID, Phone number, etc.
Dropdown
Quantity, Size, etc.
Date
Purchase date, complaint date, etc.
Decimal
Percentage values.
Dependent Fields
Country - State - City

Freshdesk has different kinds of ticket fields that let you capture various types and levels of information. For example, you could use single-line text fields to collect one-line information like the name of the company, and you could add drop-down fields to give your customers a list of options to choose from. 

Dynamic Fields:

You can make your ticket form dynamic so that the fields change based on the user input. In Freshdesk, you can add dynamic sections under the default field Type as well as any custom dropdown fields that you create
How to create Dynamic Fields: https://support.freshdesk.com/support/solutions/articles/212889-creating-dynamic-forms 

Dependent Fields:

A dependent field lets you add a hierarchical dropdown to your ticket form. It gives you an easy way to create deeper ticket categories and identify the biggest types of issues that come into your helpdesk.

How to create Dependent Fields: https://support.freshdesk.com/support/solutions/articles/37599

Here are a bunch of things you can do with your fields:  

Behavior
What it means
For Agents

Field label
Displays name of the field shown to your agents
Required when submitting the form
The agent should fill the field before submitting the form
Required when closing the ticket*
The agent should fill the field before closing the ticket
For Customers

Field label
Display name of the field shown to your customers
Displayed to customer
The customer will be able to see the field but won't be allowed to edit
Customer can edit
The customer will be able to see this field and edit the value
Required when submitting the form
The customer should fill the field before submitting the form



Article for your reference:

https://support.freshdesk.com/support/solutions/folders/74594