Ik moet werken.
English: I have to work.
In Dutch, 'moeten', 'mogen', 'kunnen', and 'willen' are modal verbs. They are used to express necessity, permission, ability, or desire.
Use these verbs to talk about what you need to do, what you are allowed to do, what you can do, or what you want to do. They are always followed by another verb in the infinitive at the end of the sentence.
Ik moet werken.
English: I have to work.
Jij mag naar buiten gaan.
English: You may go outside.
Wij kunnen Nederlands spreken.
English: We can speak Dutch.
Zij wil een appel eten.
English: She wants to eat an apple.