Need Help !

Need Help !

minä laulan
sinä laulat
hän laulaa
me laulamme
te laulatte
he laulavat

what is the meaning of minä, sinä, hän, me, te & han ?
and why the word laulaa change when use different word ? ( sinä etc. )

Notes:

The words infront are the personal pronouns

Minä - I

Sinä - You

Hän - He/She

Me - We

Te - You all (plural)

He - Them

Each personal pronoun has it's own respective verb conjugation form which is why you see that the verb "laulaa" has many different ways of bending