「ねこまっしぐら」というのは、飼い猫がエサに向かってまいしんする様子を表している。

「」、。

'Neko-masshigura' describes the way a housecat makes a beeline for its food.

Literal

''Cat-straight-ahead'' [quotative-というのは], pet-cat [subject-が] food [toward-に向かって] dashes sight [object-を] expresses.

A linguistic/cultural note about the famous cat-food commercial slogan ねこまっしぐら, now a widely recognized phrase. まっしぐら (一直ぐら) is an adverb meaning 'making a beeline, rushing straight ahead'. 向かって (toward) is the て-form of 向かう. 邁進する (まいしんする) is a formal verb meaning 'to push forward, advance straight ahead, surge ahead'. The sentence is defining a catchphrase.