Remember the small ヶ acting as a counter? Together with one and place, it makes this one place or one spot.
Just like 〜ヶ月, you'll also run into this being written as 一箇所, 一か所, or 一カ所.
Just like before, the little ヶ is actually read as か. The rest uses the on'yomi you already learned with the kanji. Just watch out 一 here is いっ instead of いち as it makes it easier to pronounce the whole word. Now, read it aloud and try yourself!
to correct one spot
to make a mistake in one spot
just one place
I made just one mistake on the test.
Before the presentation, there's one section I need to fix.
There's one place where it should be capitalized, but it's in lowercase.