Meaning of the word "sell someone/yourself/something short" in English

What does "sell someone/yourself/something short" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

sell someone/yourself/something short

US /sel ˈsʌm.wʌn/jʊərˈself/ˈsʌm.θɪŋ ʃɔrt/
UK /sel ˈsʌm.wʌn/jɔːˈself/ˈsʌm.θɪŋ ʃɔːt/
"sell someone/yourself/something short" picture

Idiom

to underestimate or undervalue someone or something

Example:
Don't sell yourself short; you have a lot of valuable skills.
It would be a mistake to sell them short in this competition.