I’m just starting algebra 2 and I do not understand a thing
Can anyone help?

Yo, we can solve for the reverse: x+x<x and get x<0

actually, even x=0 makes it false

so all values of x such that x≤0 will make it false

-3 wil make it fals
-1000324 will make it false
-π will make it false
0 will make it false
any negative number will make it false

here, I'll show you

let's say -3
-3-3>-3
-6>-3
false