You will mostly likely come across this type of record when setting up Office365 or Exchange. These are a generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX.
These records can be tricky to add to the DNS correctly so let's look at an example of an SRV record for Office 365:
You'll notice that where you would normally have the priority set in the "Priority" field, it's actually in the "Value" field followed by the port. This is typical of most SRV records so you can use the above as a template for adding this type of record to the DNS should you need to.