expression
the more one looks, the more...
A set expression meaning that as you continue looking at something, a certain quality or impression becomes stronger. Often followed by an adjective or descriptive phrase.
この絵は見れば見るほど美しい。
The more I look at this painting, the more beautiful it seems.
彼の顔を見れば見るほど、どこかで会った気がしてくる。
The more I look at his face, the more I feel like I've met him somewhere before.
A general grammatical pattern meaning 'the more... the more...'. 見れば見るほど is a specific instance of this pattern using the verb 見る.
A fixed expression formed from the conditional ～ば form of 見る (見れば) followed by the dictionary form 見る and the particle ほど, literally 'if look, to the extent of looking'. It follows the common Japanese pattern 'XばXほど' meaning 'the more X, the more...'.