问 puts a mouth 口 in the gap of a door 门 — speak, and be heard through the doorway. Scholars classify it as a sound-and-meaning pairing: 口 carries the meaning (speech), while 门 once lent its sound, back when 门 and 问 rhymed far more closely than "mén" and "wèn" do today. Either way you read it, the picture still works for a learner exactly as it did for a scribe: knock on the door, then ask.
A piece of culture
Not ashamed to ask When a student asked Confucius why a certain official had been given the posthumous title 文 — the very first character you learned on this site — Confucius answered: 敏而好学，不耻下问，是以谓之"文"也, "he was quick to learn and not ashamed to ask questions of those beneath him; that is why he is called Wen." The line gave Chinese its enduring idiom 不耻下问, "unashamed to ask" — still the standard praise for anyone secure enough to admit they don't know something. You already know both 不 and 好 from that very sentence.
Use it in a real word
问好
wènhǎo · man6 hou2
to send greetings — literally "ask good"; you already know 好