「木」 (ki) has two meanings: "tree" (the living plant) and "wood" (the material). The context usually clarifies which meaning is intended. For example, you might see many 「木」 in a park, or build a house with 「木」.

「木(き)」は、生(い)きた「木(き)」と、材料(ざいりょう)の「木材(もくざい)」を指(さ)す言葉(ことば)です。