This is one of Homer’s simile that is easy to relate to. We can think of places we have been and travel to them in our mind. That’s how quickly Hera could travel.
So he (Zeus) spoke and white armed Hera did not fail to obey. She went from the mountains of Ida to tall Olympus. Just like when the mind of a man who has travelled widely quickly moves as he thinks in his imagination “I wish I was there – or there” and there is a lot that he wishes, as quickly as that did Hera fly in her eagerness
ὣς ἔφατ᾽, οὐδ᾽ ἀπίθησε θεὰ λευκώλενος Ἥρη,
βῆ δ᾽ ἐξ Ἰδαίων ὀρέων ἐς μακρὸν Ὄλυμπον.
ὡς δ᾽ ὅτ᾽ ἂν ἀΐξῃ νόος ἀνέρος, ὅς τ᾽ ἐπὶ πολλὴν
γαῖαν ἐληλουθὼς φρεσὶ πευκαλίμῃσι νοήσῃ
ἔνθ᾽ εἴην ἢ ἔνθα, μενοινήῃσί τε πολλά,
ὣς κραιπνῶς μεμαυῖα διέπτατο πότνια Ἥρη: