俩/倆 (liǎ) is a colloquial contraction of 两个 (liǎng ge, two of them) used specifically for people. It is informal and typically follows a pronoun to form a dual: 我俩 (we two), 你俩 (you two), 他俩 (those two). Unlike 两个 it cannot be used for objects and is not used in formal writing. In northern Mandarin speech it is very common as a concise way of referring to a pair of people.