Learn Dutch: Pas als je zelf een blunder maakt, besef je hoe gênant het is. - Only when you make a blunder yourself, do you realize how embarrassing it is.

Pas translates to "only" when referring to time or a condition being met (meaning "not until"). You use alleen or slechts when talking about an exclusive amount or quantity. Since this sentence means "not until you make a blunder", pas is required.

Why are the verbs maakt and is placed at the very end of their clauses?

Both clauses use subordinate, verb-final word order. The first is triggered by the subordinating conjunction als, and the second by the question word hoe acting as a connector. Just like vandaar dat in this lesson, these words push their conjugated verbs to the very end of the clause.

Why is the main clause inverted to besef je instead of je beseft?

This is the V2 (verb-second) rule in action. The entire first subordinate clause (Pas als je zelf een blunder maakt) acts as the single first element of the main sentence. To keep the main verb in the second position, besef must come right after the comma, followed by its subject je.

Could I leave out zelf here?

Grammatically yes, but you would lose the specific emphasis of the sentence. Adding zelf translates exactly to "yourself", heavily emphasizing the contrast between watching someone else make a blunder and actually experiencing it firsthand.