What does an arrow in a chemical equation show?

Reaction arrow/yields, for example, H2 + O - -> (yields) H2O

It's like the equal sign for Chem

A chemical equation consists of the chemical formulas of the reactants (on the left) and the products (on the right). The two are separated by an arrow symbol ("→" usually read aloud as "yields") ... The equation also identifies that all the compounds are in the gaseous state.