der Kumpel
buddy
A colloquial, warm term for a good friend or mate.
Am Wochenende treffe ich mich mit ein paar alten Kumpels aus der Schulzeit.
At the weekend I'm meeting up with a few old buddies from school.

buddy / miner
Loading your saved state.
buddy
A colloquial, warm term for a good friend or mate.
Am Wochenende treffe ich mich mit ein paar alten Kumpels aus der Schulzeit.
At the weekend I'm meeting up with a few old buddies from school.

Originally, 'Kumpel' referred to a miner. Because the camaraderie among miners was very strong, the meaning expanded to good friends in general.
Mein Opa hat sein Leben lang als Kumpel im Bergbau gearbeitet.
My grandpa worked as a miner in the mining industry his whole life.
As a term for a friend, 'Kumpel' is colloquial and is used especially in spoken language. The word has a very warm and informal connotation.
Er ist ein echt guter Kumpel, auf den man sich immer verlassen kann.
He's a really good buddy you can always rely on.
Common combinations are 'ein alter Kumpel' (an old buddy) for a long-time friend or 'ein echter Kumpel' (a real buddy) for a very loyal friend. You are often 'mit seinen Kumpels unterwegs' (out and about with your buddies).
Am Freitagabend gehe ich mit meinen Kumpels ein Bier trinken.
On Friday evening I'm going out for a beer with my buddies.
You can clearly recognize the meaning 'Bergarbeiter' (miner) from the context. If people are talking about mining, coal mines, or industrial history, this is the meaning intended. In all other everyday situations, 'Kumpel' means friend.
Die Kumpel fuhren jeden Morgen gemeinsam zur Zeche.
The miners went to the coal mine together every morning.
friend / boyfriend
'der Freund' and 'der Kumpel' can both mean a man whom you know well and like. 'Freund' is neutral and fits in almost all situations. 'Kumpel' is colloquial and sounds casual, often for someone you enjoy spending time with. It feels less formal and sometimes less deep than 'Freund'. In official or serious situations, 'Freund' is usually more natural.

Nach dem Training trinkt Max noch etwas mit seinen Kumpels.
After training, Max has a drink with his buddies.
Ein Freund aus meiner Schulzeit besucht mich am Wochenende.
A friend from my school days is visiting me this weekend.