Ever since, here Apsaras and Gandharvas delight me, singing for aye the deeds of that hero, O sinless one. O son of the Kurus, this path is impassable to mortals. For this, O Bharata, as also with the view that none might defeat or curse thee, have I obstructed thy passage to this path trod by the immortals. This is one of the paths to heaven, for the celestials; mortals cannot pass this way. But the lake in search of which thou hast come, lieth even in that direction.”

In plain words: Hanuman explains that heavenly singers and dancers keep singing Rama's deeds for him. He blocked Bhima's way because this path is for the gods and no human can walk it, and he wanted to keep Bhima safe from harm or curses. The lake Bhima is looking for lies in that direction.