李(lǐ) - Li (surname), plum in Mandarin

李 (Lǐ) is one of the three commonest surnames in the Chinese-speaking world, alongside 王 and 张. It is why the character turns up so often in subtitles and news copy: it is almost never the word for a plum in modern speech, it is somebody's name.

Chinese surnames come first, so 李明 is Mr Li with the given name Ming, not a man called Li. Attach the title after the surname, never before: 李先生 (Lǐ xiān sheng), 李老师 (Lǐ lǎo shī), 李医生 (Lǐ yī shēng).

The one thing to watch is the pinyin. 李 is lǐ with a third tone, and it shares that syllable with 里 (inside) and 理 (reason). Toneless, the three are indistinguishable, so when you introduce yourself as 李 expect people to check the character.