Box 1: branch filter to exclude -
Scenario:

Continuous integration (CI) triggers cause a build to run whenever a push is made to the specified branches or a specified tag is pushed.
Box 2: branch filter to include -
You can specify branches to include and exclude. For example:
# specific branch build
trigger:
branches:
include:
- master
- releases/*
exclude:
- releases/old*
Reference:
https://docs.microsoft.com/en-us/azure/devops/pipelines/build/triggers