Feeds are aggregators that show you posts that fulfill certain criteria, such as mentioning keywords (which can include but is not limited to hashtags). They’re a lot more versatile than just hashtags. I can’t tell you why they chose the # symbol to represent feeds ┐⁠(⁠ ⁠∵⁠ ⁠)⁠┌

On your profile you have a following count, that’s where you’ll find a list of people you follow.