For MC, that means

- no sucking up to anyone because they are beautiful

- no "letting it go because she is a cute girl" 

- no awkward "I saw a naked body" 

- no sex, kissing, physical relations, including "accidental" kisses

- no romantic feelings

For the plot in general it means that there

- won't be a romantic subplot

- won't be any PDA by other characters

- may be mentions of marriage, love, characters begging for the lives of their romantic partners,...