First take Tsuen Wan Line from Tsim Sha Tsui Mtr station to Lai King and exchange Tung Chung Line. Then get off at Tung Chung MTR Station. Here you have two options now:

No.1 You can walk to Tung Chung Bus Terminus from Exit B of Tung Chung MTR Station and take Route No.23 bus to Po Lin Monastery. Giant Buddha is very close to Po Lin Monastery.

No.2 Walk from Tung Chung MTR Station to Tung Chung Cable Car Terminal and take Ngong Ping 360 Cable car to Ngong Ping 360 Cable Car Terminal. Then walk 5 minutes to Giant Buddha.