Das Bild ist hässlich.

Das is the neuter singular definite article, meaning the here.
The noun Bild is grammatically neuter, so the correct article is das:

• das Bild = the picture / the image

So Das Bild is simply the subject: the picture.

In German, every noun has a grammatical gender: masculine (der), feminine (die), or neuter (das).
Bild is a neuter noun, so it takes das in the nominative singular:

• das Bild

This gender is grammatical, not based on any natural gender.

It is in the nominative case because it is the subject of the sentence.

In Das Bild ist hässlich, the thing being described is the picture, so das Bild is nominative.

Structure:

• Das Bild = subject
• ist = verb
• hässlich = predicate adjective

German main clauses normally follow the verb-second rule (V2). That means the finite verb comes in the second position.

Here:

• Das Bild = first element
• ist = second element
• hässlich = rest of the sentence

So the sentence follows standard German word order.

Ist means is. It is the third-person singular form of sein (to be).

Because the subject is das Bild = the picture (singular), German uses ist:

• ich bin = I am
• du bist = you are
• er/sie/es ist = he/she/it is

So:

• Das Bild ist hässlich. = The picture is ugly.

Because hässlich is used after the verb sein (to be), where it functions as a predicate adjective. Predicate adjectives in German do not take adjective endings.

Compare:

• Das Bild ist hässlich. = The picture is ugly.
  
  • no ending, because hässlich is after ist
• das hässliche Bild = the ugly picture
  
  • here hässlich comes before the noun, so it needs an ending

This is a very common pattern in German.

A rough English-friendly guide is:

• häss- sounds a bit like hess, but with an ä sound
• -lich often sounds somewhat like -lish or -lihkh, depending on accent

A useful approximation is:

• HESS-likh or HESS-lish

A few points:

• ä is usually pronounced somewhat like the e in bed
• ss is a normal s sound
• ch in -lich is the soft German ch, a sound English does not have exactly

In this sentence, das is the definite article meaning the.

German das can have different jobs:

• das Bild = the picture → article
• Das ist schön. = That is beautiful. / This is beautiful. → pronoun

So the meaning depends on how it is used in the sentence.
Here, because it directly comes before the noun Bild, it is clearly the article.

Because all nouns are capitalized in German.

So:

• das Bild
• der Tisch
• die Katze

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

Bild can mean several related things depending on context, such as:

• picture
• image
• photo
• painting
• sometimes even illustration

So Das Bild ist hässlich could mean:

• The picture is ugly
• The image is ugly
• The painting is ugly

The exact translation depends on context.

Yes, hässlich is fairly strong. It usually means ugly in a direct, negative way.

Depending on context, German speakers might choose softer words such as:

• nicht schön = not beautiful / not nice
• unschön = unattractive / not very nice-looking
• komisch = strange-looking

So Das Bild ist hässlich sounds quite blunt: The picture is ugly.

Yes. That means That is an ugly picture.

Compare:

• Das Bild ist hässlich. = The picture is ugly.
  
  • You are describing a specific picture.
• Das ist ein hässliches Bild. = That is an ugly picture.
  
  • You are identifying something as an ugly picture.

Notice the adjective ending in hässliches because it comes before the noun Bild.

Yes, but the verb still stays in the second position in a normal main clause.

For example:

• Das Bild ist hässlich. = neutral statement
• Hässlich ist das Bild. = marked/emphatic, something like Ugly is the picture / The picture is what’s ugly

The second version is grammatically possible, but it sounds more stylistically marked. The original sentence is the normal, most natural version.