What does that one mean in Spanish?

Answer 1

'that one' is 'eso/esa' if it's near, 'aquel(lo)/aquella' if it's 'that one over there'

The 'o' or 'a' ending depends on the gender (masculine or feminine) of the word describing 'that' - so 'aquel hombre' (that man over there); 'esa manzana' (that apple)