Learn Dutch: Moge de toekomst je veel voorspoed brengen. - May the future bring you much prosperity.

Moge is the present subjunctive form of mogen. While the subjunctive is mostly dead in modern everyday Dutch, it survives in fixed, formal expressions like this to express a wish or hope. For a third-person singular subject like de toekomst, the regular verb would be mag, but the subjunctive uses the verb stem plus -e.

Why does the sentence start with the verb moge instead of the subject de toekomst?

When expressing a formal wish or blessing, Dutch uses a verb-first word order. This is very similar to English, which also places the verb at the start in phrases like 'May the force be with you'.

Is je the direct or indirect object in this sentence?

Je is the indirect object, meaning the prosperity is brought to you. The direct object (the thing being brought) is veel voorspoed. Because it is an indirect object, you could replace je with the stressed pronoun jou if you wanted to heavily emphasize who is receiving the prosperity.

Is this a phrase I would use in everyday conversation?

No, this is a very formal and traditional expression. Because of the formulaic subjunctive moge and the noun voorspoed (prosperity), you will almost exclusively see this written in greeting cards for weddings, graduations, or the New Year, rather than spoken aloud.