In meiner Handschrift sieht ein Buchstabe manchmal wie ein anderer aus.

Because in here describes a location or context, so it takes the dative case.

• die Handschrift = handwriting
• feminine singular dative after in → in meiner Handschrift

So meiner is the dative feminine form of mein.

German main clauses follow the verb-second rule. That means the finite verb must be in the second position, no matter what comes first.

Here, In meiner Handschrift is placed first for emphasis, so the verb sieht comes second, and the subject comes after it:

• In meiner Handschrift | sieht | ein Buchstabe ...

A more neutral version would be:

• Ein Buchstabe sieht in meiner Handschrift manchmal wie ein anderer aus.

Both are grammatical, but the original emphasizes in my handwriting.

Because the verb is aussehen, which is a separable verb.

In a main clause:

• the conjugated part goes near the front: sieht
• the prefix goes to the end: aus

So:

• aussehen → sieht ... aus

This is very common with separable verbs in German.

Yes. Ein Buchstabe is the subject.

You can tell because it is in the nominative case, and it is the thing that looks like something else.

So the structure is basically:

• Ein Buchstabe = subject
• sieht ... aus = verb
• wie ein anderer = comparison

German often uses the singular indefinite to make a general statement, just like English can.

So ein Buchstabe here does not mean only one specific letter. It means something like:

• a letter can sometimes...
• any given letter may sometimes...

This is a normal way to express a general truth.

This is a comparison:

• wie = like
• ein anderer = another one / a different one

The full idea is:

• wie ein anderer Buchstabe

But the noun Buchstabe is left out because it is already clear from context.

So ein anderer stands in for another letter.

Because it matches the omitted noun Buchstabe, which is:

• masculine
• singular
• nominative

So the implied phrase is:

• wie ein anderer Buchstabe

After ein, the adjective-like word ander- takes the ending -er in masculine nominative singular.

That is why you get ein anderer.

Because wie is used for similarity:

• Er sieht wie sein Bruder aus. = He looks like his brother.
• Ein Buchstabe sieht wie ein anderer aus. = A letter looks like another one.

Als is used for other meanings, especially:

1. comparisons of difference

   • größer als = bigger than

2. roles or functions

   • als Lehrer = as a teacher

So with aussehen meaning to look like, wie is the correct choice.

Manchmal is an adverb, and its position is somewhat flexible.

In the original sentence, it appears in a very natural middle position:

• In meiner Handschrift sieht ein Buchstabe manchmal wie ein anderer aus.

You could also hear variants like:

• Ein Buchstabe sieht in meiner Handschrift manchmal wie ein anderer aus.
• Manchmal sieht in meiner Handschrift ein Buchstabe wie ein anderer aus.

The original version sounds natural and balanced. Its position helps the sentence flow well.

In this sentence, Handschrift most naturally means handwriting—the way someone forms letters by hand.

So In meiner Handschrift means:

• in my handwriting
• when I write by hand
• in the way I write letters by hand

It would not normally mean printed text or typing.

Yes. In this context, both ideas are very close.

• another one = one more one
• a different one = not the same one

Here the natural meaning is really a different letter. The sentence is saying that one letter can resemble some other letter in your handwriting.

So in context, ein anderer is best understood as:

• a different one
• another letter

A useful way to see it is:

• In meiner Handschrift = opening phrase
• sieht = finite verb
• ein Buchstabe = subject
• manchmal = adverb
• wie ein anderer = comparison
• aus = separable prefix

So the core idea is:

• A letter looks sometimes like another one in my handwriting

More natural English reordering gives the usual meaning, but this breakdown helps show how the German grammar works.