Ich gehe mit dem Freund ins Kino.
English: I am going to the cinema with the friend.
In German, some prepositions always require the noun or pronoun that follows to be in the dative case. These are called 'prepositions with dative'.
Use these prepositions when you want to talk about things like location, direction, origin, time, or relationships with people, and the noun after the preposition must be in the dative case.
Ich gehe mit dem Freund ins Kino.
English: I am going to the cinema with the friend.
Das Buch ist auf dem Tisch bei der Lampe.
English: The book is on the table by the lamp.
Wir fahren nach Hause.
English: We are going home.
Sie wohnt seit einem Jahr in Berlin.
English: She has lived in Berlin for a year.
Der Hund sitzt gegenüber dem Haus.
English: The dog sits opposite the house.