If a guy doesn't talk to you but smiles every time you look his way, it could suggest a few possible interpretations:
He's shy or nervous: Some people are naturally introverted or shy, and they find it difficult to initiate conversations, especially with someone they may have feelings for or find attractive. Smiling could be his way of expressing interest and friendliness without having to start a conversation.
He's interested but unsure: He might be interested in you, but he's unsure how to approach you or start a conversation. Smiling could be a way of testing the waters and seeing if you respond positively before taking further steps.
He finds you visually appealing: It's possible that he simply finds you attractive and smiles as a natural reaction to seeing someone he likes looking his way.
He's being polite: Smiling can also be a polite and friendly gesture, even if he doesn't have any romantic interest. It could be his way of acknowledging your presence without necessarily wanting to initiate a conversation.
Cultural or personal differences: In some cultures or individual personalities, people may smile more frequently as a social norm, regardless of the level of interest they have in someone.
While a smile can convey positive emotions, it's essential not to jump to conclusions solely based on this gesture. If you're interested in getting to know him better, consider taking the initiative and starting a conversation yourself. This will provide an opportunity to gauge his interest more accurately and understand his intentions better.