点火 

Pinyin: diǎnhuǒ 
Meaning：Set fire 
Sentence：别随意点火。Don’t set fire as you want.

More: 

点： 

Pinyin: diǎn 
Meaning: Point; dot; o'clock
Radical: 灬
Stokes: 9
Traditional: 點
Common words/Phrase:
点击[diǎnjī] 【click, to click on】
点播[diǎnbō] 【order programme】
点名[diǎnmíng] 【roll call】
点滴[diǎndī] 【dribs and drabs】

火：

Pinyin: huǒ 
Meaning: Ammunition; anger; fire; urgent
Radical: 火 
Stokes: 4 
Traditional: 火 
Common words/Phrase:
火红[huǒhóng] 【fiery; flaming】 
火速[huǒsù] 【urgent; pressing】 
发火[fāhuǒ] 【get angry; lose one's temper】 
引火[yǐnhuǒ] 【kindle a fire】 
火锅[huǒguō] 【hot pot】