Chinese Test: Does it Really Take Half a Day?

Beginner Level 初级 (chūjí)

Conversation:                      Nǐ zài zhèr ya, zhǎo nǐ bàn tiān le. Wang Hong: 你 在 这儿呀,找    你 半   天 了。

                     Bú huì ba, nǐ zhǎole wǒ “bàn tiān?” Emily: 不 会 吧,你 找了 我 “半天”?

What does “半天 (bàn tiān)” mean here?…