Learn Swedish: Jag ska jobba ikväll. - I am going to work tonight.

When you use ska (am going to) to talk about the future, the verb that follows it must be in its base dictionary form (the infinitive). Because of ska, we drop the present tense -r from jobbar and just use jobba.

Is ska used for any future event?

ska is used specifically when someone has an intention or plan to do something. Since you are talking about your own plan to work tonight, ska is the perfect fit. If you were talking about something outside your control, like the weather, you would use a different future verb.

Why is ikväll written as one word?

In Swedish, many time expressions made of i (this / in the) plus a time period are written as a single compound word. Here, i + kväll (evening) becomes ikväll (tonight or this evening).

Does ska sound formal, like the English word 'shall'?

Historically they are related, but don't let that trick you! While 'shall' can sound very formal or old-fashioned in English, ska is the most normal, everyday way to say 'am going to' or 'will' in Swedish.