The Follow feature is to follow targeted peoples on Linkedin.
The Like feature is to like some specific posts, based on the keywords topics, connections and a lot of settings.
The purpose of this feature is to show people that you care about there contents because you like their posts.
It also helps you to increase the visibility of your profile because Linkedin algorithm likes to see profiles that interact a lot.
Then you will be able to reach more people when you share a post.