Learn Dutch: Ik heb gisteren veel gelopen.

Lopen is a verb of motion. In Dutch, you use a form of hebben (here, heb) when you are talking about the general activity of walking, as in this sentence. If you were talking about walking to a specific destination (like 'I walked home'), you would use a form of zijn (Ik ben naar huis gelopen).

Does gelopen always mean 'walked'?

Not necessarily! While it usually translates to 'walked', lopen is also frequently used to mean 'run' in Dutch (such as running a race). If you want to make it absolutely clear that you were walking for leisure, you might use the verb wandelen instead.

Why does gisteren come before veel?

In Dutch sentence structure, expressions of time (like gisteren) usually come as early as possible after the first verb. Words indicating a general amount (veel) come later, right before the past participle at the end of the sentence.

Could I say 'Ik heb veel gisteren gelopen'?

That sounds unnatural. The rule of thumb in Dutch is Time-Manner-Place. The time (gisteren) should almost always come before the manner or amount (veel).