This is the 4397th most frequent German word.
gleiche
"Same" or "equal."
In this sentence, 'gleiche' is the feminine nominative singular form of the adjective 'gleich' (same), agreeing with the feminine noun 'Idee'.
Wir haben die gleiche Idee.
We have the same idea.
In this case, 'gleichen' is the feminine singular dative form of 'gleich,' agreeing with 'Zeit' (time), indicating a point in time relative to another one.
Er kam zur gleichen Zeit wie ich.
He arrived at the same time as I did.
Here, 'gleich' is an adverb meaning 'equally,' modifying the adjective 'schnell' (fast).