This is the 4003rd most frequent French word.
cacher
To hide.
Here, 'cacher' is used reflexively ('se cache'), showing the action of taking cover or finding a hiding place, performed by the subject itself.
Le chat se cache derrière le rideau.
The cat hides behind the curtain.
The verb 'cacher' is used in the past tense here (conjugated as 'ai caché'), indicating an action of concealing something in a specified location.
J'ai caché le cadeau sous le lit.
I hid the gift under the bed.
The verb 'cacher' in this sentence is in the infinitive form and is used to express an ongoing or habitual effort to conceal feelings or internal states.