Ellen P. answered 01/25/20
Experienced Tutor in Spanish of all Levels
It's easy to confuse the words in Spanish conveying only/alone/single, etc.
"Solo/sola" means "alone", but it should be noted that "sólo" (with an accent on the first "o") means "only".
ie: Spanish: Ella estaba sola ayer en la tienda.
English: She was alone yesterday in the store.
Spanish: Nosotros sólo queremos comer pan.
English: We only want to eat bread.
"Lonely" in Spanish is "solitario", a cognate to "solitary".
Note, also, that "single", as in "unmarried" in Spanish is "soltero/soltera".