Muting someone

Alexandra • Graduating this year with a bachelors in psychology. Then med school. In a loving relationship of 6 years. Not TTC! ❤️❤️
Probably the wrong group. But when I mute someone how does that work? 
Does it block the person from seeing my posts? Does it block me from seeing their post? How do I completely block someone? Because there's certain people I would love to block completely how would I do that?