What do you call a person who doesn't want to advertise himself? He may be somebody special but doesn't like to talk about his achievement or advertise himself. What is the Adjective that describes such a trait?
Unpretentious: Not attempting to impress others with an appearance of greater importance, talent, or culture than is actually possessed. (Lexico)
Example: ‘in spite of his fame he was thoroughly unpretentious’ More example sentences
Self-effacing: Not claiming attention for oneself; retiring and modest. (Lexico)
Example: his demeanour was self-effacing, gracious, and polite.
I would say that the person was modest:
1 a : placing a moderate estimate on one's abilities or worth
1 b : neither bold nor self-assertive : tending toward diffidence
Alternatively, depending on the specific interpretation, they could also be humble:
1 : not proud or haughty : not arrogant or assertive
2 : reflecting, expressing, or offered in a spirit of deference or submission
// a humble apology
How about understated?
understated: not obvious; subtle // restrained; de-emphasized; low-key
understated: not trying to attract attention or impress people, e.g., He's very elegant, in an understated way.
Jane was always understated when it came to the value of her contributions.
It's implicit in saying that Jane is understated that she has an understated personality, manner, approach.