(Monzen no kozou narawanu kyou wo yomu;
“The child before the gate reads sutras they never learned”)
The place you live in has a strong impact on you. People who live somewhere for a long time will unconsciously be affected by their the character of the place. A child who lives near the entrance to a temple will hear the sutras being recited on a daily basis, and will eventually be able to recite the Heart Sutra themselves despite never formally learning it.
Going right to left – the verb in this full sentence is 読む (yomu), “to read,” in sentence-final form. Note that in this case the word refers to reading out loud, or reciting, rather than the simple act of looking at and understanding a text that we usually think of when we say “read” in English. The particle を (wo) points to the direct object, the noun 経 (kyou), “sutra.” The noun is modified by the verb 習う (narau), “to learn.” This verb appears in imperfective form with negative suffix ず (zu) in prenominal form (which changes it to ぬ, nu).
Everything else makes up a single noun phrases that the verb takes as its subject. The primary noun is 小僧 (kozou). The characters refer to a young priest-in-training, but by extension the term can refer to any young boy. In this case, the saying makes the most sense if you abandon the literal meaning. This noun is connected by the associative particle の (no) to compound noun 門前 (monzen), literally “in front of the gate (of a temple).”
Compare and contrast 孟母三遷.
This is the も entry for the Edo iroha karuta set.
(“Monzen no kozou narawanu kyou wo yomu de, kosodate no tame ni jibun mo terebi wo yamete mainichi dokusho suru you ni ganbatteru.”)
[“They say that the child by the temple gates unknowingly learns sutras… so for the sake of my own kids I’m working on giving up TV and reading books every day.”]