点儿 is the erhua variant of 点 (diǎn), heavily used in spoken Mandarin. As a quantifier, it describes small amounts or slight degrees. It almost always appears in the fixed phrases 一点儿 (yì diǎnr, a little bit) and 有点儿 (yǒu diǎnr, somewhat/a bit) — these are two common patterns you should memorize together. Don't try to use 点儿 alone; it always attaches to 一, 有, or other number/measure words.