Learn Danish: Appen er meget nyttig. - The app is very useful.

Danish treats most English loanwords just like native nouns. App is an en-word, so to say "the app", you simply add the standard definite suffix -en to the end, making it appen.

Why does nyttig not have an ending like -t or -e here?

Adjectives in Danish must match the noun they describe. Because appen is a singular en-word, the adjective takes its basic dictionary form, nyttig. If it were an et-word, it would be nyttigt, and if it were plural, it would be nyttige.

Does meget mean "much" or "very"?

It can mean both! When used before an adjective like nyttig (useful) in this sentence, meget translates to "very". When talking about quantity, like meget vand (much water), it means "much" or "a lot of".