Brod je težak.

Je is the 3rd person singular present-tense form of the verb biti (to be).

So the sentence is structured like:

• Brod = subject
• je = is
• težak = adjective describing the subject

Serbian usually needs je in sentences like this, just as English needs is in The ship is heavy.

Because težak agrees with brod.

Brod is:

• masculine
• singular
• nominative

So the adjective also appears in the masculine singular nominative form:

• težak = masculine singular
• teška = feminine singular
• teško = neuter singular
• teški / teške / teška = plural, depending on gender pattern

Examples:

• Knjiga je teška. = The book is heavy.
• More je teško would not normally be used for physical heaviness in the same way, but grammatically teško is the neuter form.
• Brodovi su teški. = The ships are heavy.

Brod is in the nominative singular because it is the subject of the sentence.

In Brod je težak, the sentence is simply stating something about the ship, so the basic subject form is used.

This is the normal dictionary form of the noun:

• brod = ship

Serbian does not have articles like English a/an/the.

So brod can mean:

• a ship
• the ship

Which one is meant depends on context.

That means Brod je težak could mean either:

• The ship is heavy
• A ship is heavy

In real use, context usually makes it clear.

Yes. Težak can mean both:

• heavy in a physical sense
• difficult / hard in a figurative sense

Examples:

• Kofer je težak. = The suitcase is heavy.
• Ispit je težak. = The exam is difficult.

In Brod je težak, the natural meaning is physical heaviness.

Yes. Serbian word order is more flexible than English word order.

The neutral, basic order is:

• Brod je težak.

But you might also hear:

• Težak je brod.
• Brod težak je is much less natural in normal speech

Changing the order usually changes emphasis, not the core meaning.

For example:

• Brod je težak. = neutral statement
• Težak je brod. = emphasis on heavy

The letter ž is pronounced like the s in measure or the g in genre for many English speakers.

So:

• težak sounds approximately like TEH-zhak

Also:

• brod = one syllable, roughly brohd
• je = usually like ye

So the full sentence sounds approximately like:

• Brod ye TEH-zhak

Normally, no.

In present-tense sentences with to be plus an adjective, Serbian usually keeps the form of biti:

• Brod je težak. = correct

Leaving out je would sound incomplete or ungrammatical in standard Serbian.

This is different from some languages where the present-tense to be can be omitted.

You make it negative by changing je to nije:

• Brod nije težak. = The ship is not heavy.

This is the normal way to negate je in this kind of sentence.

A very common way is:

• Da li je brod težak? = Is the ship heavy?

Another common spoken pattern is:

• Je li brod težak?

Both are used, and both mean the same thing.

The plural is:

• Brodovi su teški. = The ships are heavy.

Changes:

• brod → brodovi = ships
• je → su = are
• težak → teški = masculine plural adjective form

So all the parts adjust to the plural.

Brod usually means ship, though in some contexts English may translate it more generally depending on size and situation.

Some related words:

• brod = ship
• čamac = small boat
• lađa = boat/ship, often more literary or traditional depending on context

For a beginner, brod = ship is the safest basic meaning.

That is just the normal masculine singular form of this adjective.

A useful thing to notice is that when the adjective changes form, the stem may look a little different:

• masculine: težak
• feminine: teška
• neuter: teško

So the masculine form has -ak, but other forms show the stem more clearly:

• tešk-

This kind of alternation is normal in Serbian and is worth getting used to early.