"The Netherlands has many beaches."
Translation:Nederland heeft veel stranden.
Is correct too. There is a subtle difference where veel just means many and vele can imply that there are many distinct beaches or something. It makes them sound a little less a dime a dozen.
Edit: it can also means many many instead of just many. "Ik moest vele maanden wachten" versus "ik moest veel maanden wachten". The first one sounds more tedious.
According to the notes for Adjectives because "If no article at all comes before a het-word, then the adjective does not get the -e ending either."
Did you see an "s" behind Nederland? No, you did not, therefore it is a word that is not plural, it is a singular noun (for the entire country of provinces). Then we know it is a "thing" not a person. Please conclude that the subject is a Thing in the singular form: an "It". Look at the verb conjugation list for Het (3rd person singular). See that it uses the form "heeft" not "heb"? Hebt is verb form to use for the 2nd person for "YOU" personal pronoun (not a thing). I hope this helps you.
Basically, use 'heeft' with hij, zij, ze and het (which is what Nederland would be in this sentence), and 'hebt' with je and jij. For u, you can use either form.
Here's a link to info on how to conjugate verbs for present simple tense, including hebben: https://forum.duolingo.com/comment/3762671/Grammar-The-Dutch-present-simple.