And a few words, like hobo, can take either form. Potatoes and tomatoes probably became -es words long ago by analogy with the word toes. Words like photos and pros are abbreviations, and words like solos and studios and folios are foreign.
The song 'Ending Credits' by Opeth is easy to play and technically it is a solo as it is an instrumental.
solos
In the plural, it's solos.
The general rule in English usage is that if the noun ends in a vowel followed by o you add an s; if it ends in a consonant followed by o you add es. There are, however, a number of exceptions to the latter rule: pianos, solos, photos, memos, etc.]
Some words ending in o that form their plural by adding s only include: pianos, duos, solos, tacos.
Solos
Solos
The solos in the band performed rock music.
Guitar Solos was created in 1974-07.
A cello is sometimes used in solos depending on the music
Saxophone Solos was created on 1975-12-09.
soles solos sofas soaks soars socks sodas soils songs souls and so on ...