One of the first things a student of Japanese learns about the language is its different set of sounds. Japanese has five pure vowel sounds — あ (ah), い (ee), う (oo), え (eh) and お (oh) — which combine with roughly nine consonants. It’s a more limited set of sounds than in English, and with more limited combinations, students of Japanese realize, to their immense frustration, that many words in Japanese have nearly identical 発音 (hatsuon, pronunciation).
Personally, I discovered this in an early lesson about directions, when I learned that an incorrect pronunciation of 橋 (hashi, bridge) would refer to 箸 (hashi, chopsticks). Even worse, hashi is also a reading for 端 (end). The pronunciations do slightly differ: 箸 is pronounced from high to low, with more emphasis on the ha, while 橋 and 端 are pronounced low to high, with more emphasis on the shi. But that doesn’t make it any easier for a student to differentiate. And these nightmarish 同音異義語 (dōon’igigo, homophones) are rampant in Japanese: nami is both 波 (wave) and 並 (average); take is 竹 (bamboo), 丈 (height) and 岳 (mountain peak); hata is 側 (near), 畑 (field), 旗 (flag) and a bunch of other words, too.
This inherent trait of Japanese leads to the frequent appearance of puns and double meanings. This wordplay (or sometimes, coincidental overlapping) is found throughout Japanese culture, from ancient poetry to New Year’s dishes to 親父ギャグ (oyaji gyagu, dad jokes).