「高い」(takai) is an い-adjective with multiple meanings: "high" (for height), "tall" (for people/buildings), or "expensive" (for price). You can say "高い山" (takai yama) for a "high mountain" or "高い車" (takai kuruma) for an "expensive car."

「高い」(たかい)は「値段が高い」や「高さがある」という意味のい形容詞です。例：「高いビル。」