What does this mean on twitter?

[Dill]

that means the their cousins are better than yours

[Chloe]

This sign: > is called the greater-than sign. In this case, the person who posted that is trying to say "my cousins are better than your cousins."

[unknown]

">" determines that whatever is on the left of it is larger. Our math teachers at grade school taught us to think of "alligators eating what's bigger". So, basically, 100 > 1, and their cousins > your cousins.