The word "uso" is the verb "usar" ("to wear") conjugated in the present "yo" form. You would write "usa" to say, for example, "She doesn't wear elegant clothes" ("Ella no usa ropa elegante"). All of the conjugations of usar would be:
-Yo uso = I wear
-Tú usas = You wear
-Él/ella/usted usa = He/she/you (formal) wear
-Ellos/ellas/ustedes usan = They (male or mixed)/they (all female)/all of you wear
-Nosotros usamos = We wear
Hope that helps!
Clothes is the plural of cloth. It has changed pronunciations over time. you are wearing multiple pieces of cloth hence clothes- just like there are instances where you would use "peoples" and not "people". bed linens (sheets and blankets) used to be called "bed clothes" you wrapped cloth around your pallett, cuchion or stuffed mattress.
Some words don't change based on the gender of the word they modify. This for example happens with adjectives ending in -e (like inteligente and elegante) ending in a consonant (gris, marrón) and ending with -or (mejor and peor). There are others but this is just to illustrate.
After checking the comments in the lesson and the comments here in the online forum, this particular question hasn't been addressed: I wrote, "No uso ropa elegante." It was marked wrong for not using yo at the beginning of the sentence. I thought it was optional when the verb is self explanatory (it includes the amount of people it's referring to i.e., uso, usas, usamos, etc.). Why was it marked wrong and is this reportable?