Learn Portuguese (Portugal): O arame farpado rasgou a roupa dele.

Yes, but roupa is most commonly used as a collective noun for clothes in general, similar to the word clothing in English. You would use the plural roupas when emphasizing distinct, separate garments or outfits, but the singular is the most natural choice here.

Why does the sentence use a roupa dele instead of a sua roupa?

While sua is grammatically correct, it can mean his, hers, yours, or theirs. Using dele directly after the noun completely removes this ambiguity, making it strictly mean his. Native speakers strongly prefer this structure in everyday communication.

What is the origin of the adjective farpado?

It derives from the noun farpa, which means a splinter, sliver, or barb. By adding the suffix -ado to create an adjective, arame farpado becomes the exact equivalent of barbed wire.

Is the verb rasgar only used for tearing fabrics?

No, rasgar is quite versatile. You can use it for tearing paper, but it also applies to deep physical cuts, tearing a muscle, or even metaphorically, such as a road tearing through a landscape.