くらい is the most common way of saying “about” or “approximately” in Japanese. It will usually be introduced appended to a counter to let us say “about five minutes” or “about ten dollars”. Either くらい or ぐらい can be used; although when the particle is appended directly to a noun (e.g. a counter) then it will normally be pronounced ぐらい. Incidentally, the kanji is 位, but the hiragana is more often used in writing.
あと５分ぐらいで行けると思います。
I think I can go in about five minutes.
１５ドルぐらい持っています。
I have about $15.
荷物が届くまでは３週間ぐらいかかる。
It will take about three weeks until the parcel arrives.
何時ぐらいに来られそうでしょうか？
Roughly what time do you think you will be able to get here?
イタリアが大好きで６回ぐらい行ったことがあるよ。
I love Italy and I’ve been there about six times.
Expressing Extent: “To the extent that…”
While くらい/ぐらい is first introduced as “approximately” for numbers, it has a second, equally important function (frequently tested on the JLPT N3): expressing the extent or degree of an action or state. In this usage, it translates closer to “to the extent that…” or “so much that…”.
すぐに食べたくなるぐらいおいしそう！
It looks so delicious I want to eat it straight away!
手で触ったら火傷してしまうぐらいフライパンが熱いから気をつけてね。
The frypan is hot enough to burn you if you touch it, so be careful.