Er findet das Haus hässlich.

Not in this sentence. With finden, German can mean either:

• to find / discover something
• to find / consider / think something is a certain way

Here it has the second meaning:

• Er findet das Haus hässlich. = He thinks the house is ugly. / He finds the house ugly.

So hässlich tells you this is not about locating the house, but about his opinion of it.

Because it works as a kind of description of the object:

• das Haus = the thing being talked about
• hässlich = what he considers it to be

So the structure is:

• Er = subject
• findet = verb
• das Haus = direct object
• hässlich = object complement / descriptive adjective

This is very similar to English:

• He finds the house ugly.

German often puts this describing word after the object in sentences like this.

Because here hässlich is not directly in front of a noun. It is being used predicatively, not attributively.

Compare:

• das hässliche Haus = the ugly house
  
  • here the adjective is before the noun, so it takes an ending: hässliche
• Er findet das Haus hässlich. = He finds the house ugly
  
  • here the adjective stands separately, so it has no ending

This is a very important German pattern:

• adjectives before nouns usually take endings
• adjectives after verbs usually do not

Das Haus is the direct object of findet, so it is in the accusative case.

The noun Haus is neuter, so:

• nominative: das Haus
• accusative: das Haus

They look the same, which is why you do not see a change here.

Compare with a masculine noun, where the article would change:

• Er findet den Film hässlich. would be wrong because Film is masculine and not something usually called ugly, but grammatically den shows the accusative.
• better example: Er findet den Hund süß. = He finds the dog cute.

So in your sentence, das Haus is accusative, even though it looks the same as nominative.

Because er is the pronoun meaning he, and it matches the verb form findet.

In a normal main clause, German usually puts the finite verb in second position, and the subject often comes before it:

• Er findet ...

So:

• Er = subject
• findet = 3rd person singular verb

If the word order changed, the subject could still stay the same because of the verb form and context:

• Das Haus findet er hässlich.

This still means He finds the house ugly, but now das Haus is moved to the front for emphasis.

Because all German nouns are capitalized.

So:

• Haus is a noun, so it gets a capital letter
• hässlich is an adjective, so it stays lowercase

This is one of the most noticeable spelling rules in German.

It is the 3rd person singular present tense form of finden.

Present tense of finden:

• ich finde
• du findest
• er/sie/es findet
• wir finden
• ihr findet
• sie/Sie finden

So Er findet means he finds or, in this context, he thinks/is of the opinion that.

Yes, but it is a different structure.

• Er findet das Haus hässlich.
  = He finds the house ugly.
  = a compact way to give someone’s opinion

• Er denkt, dass das Haus hässlich ist.
  = He thinks that the house is ugly.
  = a full clause after denken

You may also hear:

• Er denkt, das Haus ist hässlich.
  This is common in speech, with the dass omitted.

finden is often the most natural choice when talking about personal judgments like:

• Ich finde den Film langweilig.
• Sie findet das Essen lecker.

Yes. Er findet das Haus hässlich is in the present tense.

Depending on context, English might translate it as:

• He finds the house ugly
• He thinks the house is ugly

If you wanted the past tense, you could say:

• Er fand das Haus hässlich. = He found/thought the house was ugly.

Yes, but then the meaning structure changes slightly.

• das hässliche Haus = the ugly house
  
  • here ugly is part of the noun phrase itself
• Er findet das Haus hässlich. = He finds the house ugly
  
  • here ugly is his opinion about the house

So both are correct, but they do different jobs.

Compare:

• Er sieht das hässliche Haus. = He sees the ugly house.
• Er findet das Haus hässlich. = He thinks the house is ugly.

A rough guide:

• häss- sounds a bit like hess but with the German ä
• -lich ends with the soft German ich sound, not an English k sound

Very roughly: HESS-likh, but with a softer final sound than kh

Important points:

• ä is not exactly the same as English a
• ch in -lich is the soft sound heard in words like ich, nicht, milch

A native-like pronunciation is hard to show in English spelling, but the main thing is:
do not pronounce it like hag-slick or with a hard k at the end.

Yes, as long as the finite verb stays in second position in a main clause.

Standard order:

• Er findet das Haus hässlich.

Possible variation:

• Das Haus findet er hässlich.

This puts more emphasis on das Haus.

What you usually cannot do in a normal main clause is move findet away from second position:

• ❌ Er das Haus findet hässlich.

So the key rule is: in a German main clause, the conjugated verb is typically second.