For many years, the adverb sense of this word was written with an accent: "sólo." Nowadays, all senses of this word are written without an accent: "solo."
pasa los días solo en su cuartohe spends the days alone o on his own in his room;iré soloI'll go alone o on my own;dejar solo a algnto leave sb alone;me quedé soloI was left alone;habla solohe talks to himself;se quedó solo a los siete añoshe was left an orphan o alone in the world at seven
estar más solo que la unato be all on one's own
es tonto como él solohe's as stupid as they come
lo hace como él solohe does it as no one else can
se queda solo contando mentirashe's as good a liar as you'll find
más vale estar solo que mal acompañadoit's better to be on your own than in bad company
2(solitario)lonely
me siento muy soloI feel very lonely
3(único)
su sola preocupación es ganar dinerohis one o only concern is to make money;con esta sola condiciónon this one condition;hay una sola dificultadthere is only o just one problem;no hubo ni una sola objeciónthere was not a single objection
solo quiero verloI only o just want to see it;es solo un tenientehe's only a lieutenant;he's a mere lieutenant;no solo A sino también Bnot only A but also B;solo con apretar un botónat the touch of a button;me parece bien solo que no tengo tiempothat's fine, only o but I don't have the time;ven aunque solo sea para media horacome even if it's just for half an hour;con solo que sepas tocar algunas notaseven if you only know how to play a few notes;solo con que estudies dos horas diariasby studying for as little as two hours a day;tan soloonly;just;solo que ...except that ...;viajará sólo un par de díashe'll only be away for a couple of days
In the past the standard spelling for this adverb was with an accent ([sólo]). Nowadays the [Real Academia Española] advises that the accented form is only required where there might otherwise be confusion with the adjective [solo].