Question

what do these symbols mean? ∈,∉,⊂,⊆

Answer 1

I don't really know how to describe them but i know how to use them.
Here are some examples of how they are used:

R ∈ 7 : means R is an element of 7
R ∉ 7 :means R is not an element of 7

⊂ : means "a subset". e.g. R⊂T means that for every element of R is also an element of T.
i don't know about the last sign but i guess is somehow related to this " ⊂ "

Answer 2

Is an element of, is not an element of, is a proper subset of, is a subset of, respectively.

Answer 3

@across, thanks for the insight. Trully appreciated.