"A red coat."
Translation:Un abrigo rojo.
Abrigo - coat, shelter (in specific contexts only), shelter from cold (not directly translatable in english)
Saco - sack, bag, light coat such as a formal jacket (only in Latin America), also the first person present tense of sacar (to take out, to remove)
I recommend bookmarking a Spanish dictionary to help with this sort of thing. I personally prefer Spanish Dict, despite its annoying adverts, because it has detailed definitions, examples, a conjugation chart for each verb with pronunciations, and much more.
FULL DISCLOSURE: Native English speaker - US, Southern Appalachian dialect. Other uses of English may vary. Advice about Spanish should be taken with a grain of salt.