Answer 1

Go to the links given below where you can find these with example for better understanding.
Rowspan:-
https://www.w3schools.com/tags/att_td_rowspan.asp
Colspan:-
https://www.w3schools.com/tags/att_td_colspan.asp

Answer 2

rowspan is actually span your rows (from up to down) if you set value 2 or 3 then, it will combine 2 or more row boxes...

On the other hand, colspan span your columns (from left to right), if you set value of 2 or 3 or something else. It would combine 2 or more columns boxes...

Try experimenting.....have fun !!! 👍👍👍