How do you read this?

The 2 or 3 Letters on each square are the elements atomic symbol. the number on the top of the table is how many electrons the element's atom has.

We have a whole other section about Atoms.
So check that one out!
Anyway the table is organized in many columns and rows. Some columns are named...
like the Nobel gases or the alkali metals
maybe even the halogens!
The Element Atoms can meet and combine to because a compound. H20 is a compound.