The 火 radical represents fire and flames. As the bottom variant 灬 (four dots), it appears in kanji related to heat, cooking, and fire. At N5, 火 (Tuesday in Japanese, literally 'fire day') is the core kanji.

火 sits on the left in 焼 and 灯, and at the bottom it flattens into 灬, four short strokes called れっか, seen in 点, 照, 熱 and 無. The change is dramatic enough that many learners never connect 灬 with fire at all. When you see those four short strokes along the bottom of a kanji, fire or heat is the first guess to try: 熱 (heat), 焼 (grill), 照 (shine). It is a reliable guess but not a rule; 無 (nothing) ends the same way for unrelated historical reasons, so treat 灬 as strong evidence rather than proof. One counting habit to fix: 灬 is four strokes, not one, even though it looks like a line of dots, and stroke count matters when you look a kanji up by radical.