kaban ni ana wo mitukemasita.

In this sentence, に marks the location where something was found.

So:

• かばんに = in/on the bag
• 穴を見つけました = found a hole

Together, the structure is:

• A に B を 見つける = find B in/on/at A

So かばんに穴を見つけました means I found a hole in the bag.

Even though に often gets introduced as meaning to or in, its real job is broader: it marks a target, place, point, or result depending on the sentence.

Because 穴 is the thing that was found, and を marks the direct object of the verb.

Here:

• 穴 = hole
• 穴を見つけました = found a hole

So the sentence is built like this:

• かばんに = in the bag
• 穴を = a hole
• 見つけました = found

The thing being found is the hole, not the bag, so 穴 gets を.

見つける means to find or to discover.
見る means to see or to look at.

That difference matters here:

• 穴を見ました = I saw a hole
• 穴を見つけました = I found/noticed a hole

So 見つけました suggests the speaker noticed something that they discovered was there. It is a better match for English found.

Because Japanese often leaves out the subject when it is obvious from context.

So even though English usually needs something like I found a hole in my bag, Japanese often just says:

• かばんに穴を見つけました

Depending on context, this could mean:

• I found a hole in my bag
• I found a hole in the bag
• even sometimes We found a hole in the bag

Japanese relies heavily on context, so pronouns such as I, you, and he/she are often omitted.

Japanese usually does not mark articles like a or the, and it also often omits possessives like my when they are understood from context.

So かばん can mean:

• a bag
• the bag
• my bag
• your bag

Which one is correct depends on the situation.

For example, if you are talking about your own bag, かばんに穴を見つけました will naturally be understood as something like:

• I found a hole in my bag

Yes, that is a very good literal breakdown.

Word by word:

• かばん = bag
• に = in/on
• 穴 = hole
• を = object marker
• 見つけました = found

A natural English rendering is:

• I found a hole in the bag
• or, in context, I found a hole in my bag

So the basic pattern is:

• [place] に [thing] を 見つけました
• found [thing] in [place]

見つけました is:

• past tense
• polite form

The dictionary form is:

• 見つける = to find

Related forms:

• 見つけます = find / will find (polite non-past)
• 見つけました = found (polite past)
• 見つけた = found (plain past)
• 見つけませんでした = did not find (polite past negative)

So this sentence is politely saying that the finding already happened.

No. In normal Japanese writing, this would usually be written without spaces:

• かばんに穴を見つけました。

Spaces are often added only in beginner materials to make the sentence easier to read.

Yes, it is understandable and basically natural.

It clearly means that someone discovered a hole in a bag.

That said, native speakers might also say things like:

• かばんに穴があいていました。
  There was a hole in the bag / The bag had a hole in it.

• かばんに穴があるのを見つけました。
  I found that there was a hole in the bag.

Your original sentence is fine, but these alternatives can sound a little more natural depending on context.

かばんの穴 means the bag’s hole or the hole in the bag as a noun phrase.

That is different from the sentence structure here.

Compare:

• かばんに穴を見つけました。
  I found a hole in the bag.

• かばんの穴を見つけました。
  I found the bag’s hole / I found the hole in the bag.

The second version focuses more on the hole belonging to the bag as one combined noun phrase.
The original version, かばんに穴を見つけました, emphasizes the location where the hole was found.

Both can work, but に is very natural when talking about finding something in/on a place.