When customers submit a support request, they'd also like to know when they can expect a response (and a resolution) from you. A service level agreement (SLA) policy lets you set standards of performance for your support team. You can set SLA policies for the time within which agents should respond to and resolve tickets based on their priorities, and set up automatic escalation rules to notify specific agents about SLA violations.

You can set targets for: 
  • The very first response that you send to the customer
  • Every response that's sent after the first response ( Available from Estate) 
  • The ticket resolution 

Editing the default SLA policy:
  • Login to your Freshdesk
  • Go to Admin > General Settings > SLA Policies
  • Because how fast you're required to respond to tickets depends on its priority, you can set-up a different SLA target for the different ticket priorities- urgent, high, medium and low
  • Choose whether the SLA timer should be calculated based on Business or Calendar hours.
  • If you'd like to enable escalations when service levels are violated, make sure that the Escalation option button is toggled on.

Multiple SLA policies:

You can either have a single SLA policy for all tickets or have different SLA policies for different types of tickets. As an example, you can have a shorter SLA target for tickets from Social media or VIP customers.

Steps to create a new SLA policy:
  • Click on the Add policy button on the SLA Policies page. You'll then have to define SLA targets for each ticket priority, just like you did with the default policy.
  • Choose the type of tickets for which you want to have the SLA policy to work on. For instance, you can have different SLAs for tickets from Social Media.
  • These are the conditions you can use to trigger a specific SLA policy:

Company -For example, you might want to trigger a particular SLA policy only for customers who have purchased your Priority Support Subscription.
Group - if you want this policy to apply only for specific Agent Groups, you can select them here. For example, you might want to define a different set of service levels for your finance group which has to process refunds.
Product - if you're supporting multiple products or brands through a single Freshdesk account, you can define which product(s) this particular policy must be applied to.
Source - you might want to set a different service level target for tickets coming in through Twitter, as compared to those through email.
Type - you can select the SLA to be enforced based on the type of problem that you are facing; such as a billing problem, or a potentially serious bug as examples.
Contact segment and company segment - As examples, if you have a list of customers that fall under a "VIP" category, or use a specific product of yours, you can create a separate policy for them.
Setting SLA targets for every response:
https://support.freshdesk.com/support/solutions/articles/50000001634-slas-for-every-response#anchor4

Article for your reference - https://support.freshdesk.com/support/solutions/articles/37626-understanding-sla-policies