Learn Dutch: Je moet de server beter beveiligen. - You must secure the server better.

This is a great refresher on standard Dutch word order. When using a modal verb like moeten, the conjugated modal verb (moet) takes the second position, and it pushes the main action verb (beveiligen) to the end of the clause in its full infinitive form.

Is beter an adjective or an adverb here, and why is it placed after the object?

Here, beter is an adverb describing how you must secure the server. In Dutch, adverbs of manner (how something is done) typically come after the specific direct object (de server) and right before the verbs at the end of the sentence.

How does the verb beveiligen relate to the Dutch word for "safe"?

It comes directly from the adjective veilig, meaning "safe." Adding the prefix be- and the suffix -en turns it into a transitive verb (a verb that takes a direct object) meaning "to make safe," "to protect," or "to secure."

Why use je instead of jij in this context?

Je is the unstressed form of "you." Unless you specifically want to emphasize who must secure the server (meaning "You must do it, not someone else"), the unstressed je is the natural and most common choice for general instructions.