What's the difference between 也 (yě) & 和 （hé)?
也 means "also" whereas 和 means "and."  Adverb vs. conjunction.

So for example, to say "I am also a student" you could write 

我也是学生。


But you cannot write 

我和是学生。


Additionally, 也 cannot function as 和。To say "My friend and I are watching a movie" you could write

我和我的朋友在看电影。


But you cannot write 

我也我的朋友在看电影。


Here are some links you might want to check out (both on ChineseGrammarWiki): 


The "also" adverb "ye" 
Expressing "and" with "he"