Learn Hardcore Dutch: Hij kan prima fietsen.

Kan is the 3rd person singular present tense of the modal verb kunnen, which means to be able to or can. It expresses ability—here, that he is able to cycle.

Why is fietsen placed at the end and why isn’t there a te before it?

With Dutch modal verbs like kunnen, you follow directly with an infinitive without te. In main clauses the finite verb (kan) stays in the second position (after the subject Hij), and any non-finite verbs (here fietsen) move to the very end.

What does prima mean here, and why is it used instead of goed?

Prima is an adverb meaning great, just fine, or very well. It’s a little stronger and more conversational than goed (“well”), so Hij kan prima fietsen suggests he cycles really well, even effortlessly.

Could fietsen in this sentence be a noun (cycling) instead of a verb?

No. In Hij kan prima fietsen it’s the infinitive verb to cycle. To use it as a noun cycling, you’d need the article: het fietsen.