Great question.

it hides your content

Reputation does not hide any content. The owner of the frontend you are currently using does.

whats reputation

Reputation is a number (usually displayed next to your username - 55 for you atm) that reflects how many upvotes/downvotes you got historically. It has little to do with what people think of you because that is often separated from the voting process.

yours so low

"Low" is not the correct way to understand it. Low Reputation is anything around 25 (the initial value). That means noone knows you yet. The further away you get from 25, the more recognition you have - people experienced the urge to vote on your posts.
The recognition can be positive (above 25) or negative (below 25 and into negative numbers).

why is yours so

Reputation is stake-based. A huge account decided I am worthy. You can either click my username and explore my posts and their walls of text full of Kremlin-based writing techniques. Or save some time and wait till they drop one here as well.