Learn Hardcore Swedish: Jag vill vara i solen idag.

vill is the present-tense form of vilja (to want). It acts like an English modal verb—expressing desire—and is directly followed by a bare infinitive (vara).

Why isn’t there an att before vara, and why is vara in the infinitive form?

After a modal verb such as vill, Swedish omits the infinitive marker att. The main verb stays in its bare infinitive form: vill vara, not vill att vara or vill är.

Why do we use i instead of på with solen?

In Swedish, i generally means “in” or “within,” while på means “on” or applies to certain fixed locations (e.g. på bordet = on the table). Since you’re “in the sun,” you use i solen.

Why is solen in the definite form, with the suffix -en?

Because you’re referring to “the sun.” The noun sol (sun) takes the definite suffix -en to become solen (“the sun”), just like “in the sun” in English.

Can I place idag at the beginning of the sentence, and if so, what word-order rule applies?

Yes. Swedish follows the V2 (verb-second) rule: if you start with an adverbial like idag, the finite verb must be in the second position, followed by the subject.
Example: Idag vill jag vara i solen.

Is it written idag or i dag, and is there a difference?

Both idag and i dag are correct, but the one-word form idag is more common in modern Swedish. The meaning remains “today.”

How else can I express “I want to sunbathe today” in Swedish?

You can use the verb sola (to sunbathe): Jag vill sola idag. It’s a more concise way to say you want to spend time in the sun.

How should I pronounce jag vill vara i solen idag?

A simple rendering is yag vill VAR-ah ee SOO-len ee-DAHG.

j in jag sounds like y in “yes.”
The o in solen is like oo in “book.”
Stress falls on VAR, SOO and DAHG.