「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(たか)い」(たかい)は「値(ね)段(だん)が高(たか)い」や「高(たか)さがある」という意(い)味(み)のい形(けい)容(よう)詞(し)です。例(れい)：「高(たか)いビル。」