Question

What do the symbols in parenthesis indicate?
CaCl2(aq) + 2AgNO3(aq)) → Ca(NO3)2(aq) + 2AgCl(s)

Answer 1

aq means it's soluble in H2O by default

s means it's solid, not soluble.

Answer 2

It indicates physical state of that compound.
aq is for aqueos.
s is for solid
l is for liquid and
g is for gaseous state.

Hope this helps you.