〜そうです（様態）
Looks like…; looks about to…machine translation
FormationVerb ます-form (drop ます) / adjective (drop い・な) + そうです
〜そうです (appearance) expresses an impression based on what you see directly: おいしそう (looks delicious), 楽しそう (looks fun). With verbs, it means "looks about to happen": 雨が降りそうです (it looks like it's about to rain), 落ちそうです (it looks like it's about to fall).
How to connect: verb ます-form with ます dropped (降ります → 降りそう), い-adjective with い dropped (おいしい → おいしそう), な-adjective with な dropped (元気 → 元気そう). Two exceptions you must remember: いい → よさそう, ない → なさそう. This pattern is NOT used with nouns — don't say 学生そう; use 学生のようだ or 学生みたい instead.
When modifying, 〜そう behaves like a な-adjective: 楽しそうな人 (a person who looks cheerful), 楽しそうに遊ぶ (to play looking like they're having fun). Don't confuse it with the hearsay 〜そうです: おいしそうです is "looks delicious" (seen with your own eyes), while おいしいそうです is "I hear it's delicious" (heard from someone else) — a single い apart, but completely different meanings.
Examples
このケーキ、おいしそうですね。
This cake looks delicious, doesn't it?
雨が降りそうですから、傘を持って行きましょう。
It looks like it's about to rain, so let's take an umbrella.
子どもたちは楽しそうに遊んでいます。
The children are playing and look like they're having a great time.