Bacon is so tasty that I can eat an unlimited number of strips.
About how many tickets have you sold so far?
How many stickers do you want? For a large amount, we could give you a discount.
You have flat objects but what amount of flat objects? This word is asking that question: "how many flat objects are there?" If this doesn't make sense, think back to words like 何回 or 何年 which ask "how many ____" just like this one.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.