Meaning of “through” - Learner’s Dictionary

through

preposition us uk /θruː/
ONE SIDE TO ANOTHER

A2 from one end or side of something to the other:

The River Seine flows through Paris.
The sun was shining through the window.
She cut through the wire.

More examples

START TO END

B1 from the start to the end of something:

He worked through the night.
The phone rang halfway through the programme.
BECAUSE OF

B1 because of someone or something, or with someone's help:

I got the job through my mum's friend.
He became ill through eating undercooked meat.
UNTIL US UK/US to

from a particular time until and including another time:

The store is open Monday through Friday.
I worked there from May through September.

(Definition of “through preposition” from the Cambridge Learner’s Dictionary © Cambridge University Press)