Translation:I bought a lot of clothes.
I believe (correct me if I'm wrong) ふく refers to clothes in general, whereas ようふく means specifically western clothes. In addition, わふく means traditional Japanese clothes. For example, a shirt would be "ようふく” and a kimono would be "わふく" but either could fall under the umbrella term "ふく”.
I believe 洋服, though seen as quite different to 和服 or 民族服, is pretty much standardised in Japan. They iterate that it is not traditional attire whilst preferring it to simply 服, which is an umbrella term. Take it as similar to saying, "I bought a vehicle." People would more commonly say whether they ventured for a motorbike, a car, or some such. Hope that helps!
The particle is attached to the word ようふく, so you can't separate it like that. を follows the direct object (who or what receives the action of the verb).
What did you buy?
洋服を買いました (youfuku o kaimashita)
I bought clothes.
What did you eat?
ご飯を食べました (gohan o tabemashita)
I ate rice.