Судьба иногда меняется.

• судьба = fate, destiny
• иногда = sometimes
• меняется = changes, is changing

So the sentence literally comes out as Fate sometimes changes or Destiny sometimes changes.

Судьба is in the nominative singular form because it is the subject of the sentence — the thing that does the action.

Dictionary form:

• судьба = fate / destiny

Since the sentence is about fate doing the changing, nominative is the expected case.

Меняется is:

• 3rd person singular
• present tense
• from the verb меняться

So it means:

• it changes
• it is changing

Because the subject судьба is singular, the verb is also singular.

The -ся ending is a very common Russian verb ending. It often makes a verb reflexive or gives it a more intransitive meaning.

Here, меняться means to change in the sense of to undergo change.

Compare:

• менять = to change something
• меняться = to change, to be changing

So:

• Он меняет план. = He changes the plan.
• План меняется. = The plan changes / is changing.

In your sentence, судьба меняется means fate changes, not someone changes fate.

Because меняет and меняется are different verbs in meaning.

• меняет comes from менять = to change something
• меняется comes from меняться = to change

So:

• Он меняет судьбу. = He changes fate.
• Судьба меняется. = Fate changes.

In your sentence, судьба is not the object being changed by someone else; it is the subject that changes.

It is present tense.

Russian present-tense forms only exist for imperfective verbs, and меняться is imperfective.

Here it expresses a general idea:

• Fate sometimes changes
• Destiny can change sometimes

It is not really talking about one completed future change. If you wanted a future/completed idea, Russian would usually use a perfective verb such as измениться in a different form.

Russian has no articles like English a/an/the.

So судьба can mean:

• fate
• the fate
• a fate

The exact meaning depends on context. In this sentence, English usually translates it most naturally as Fate sometimes changes or Destiny sometimes changes.

Yes. Russian word order is more flexible than English.

Your sentence:

• Судьба иногда меняется.

Another natural version:

• Иногда судьба меняется.

Both mean essentially the same thing: Fate sometimes changes.

The difference is mainly emphasis:

• Судьба иногда меняется puts судьба first, so the topic is fate
• Иногда судьба меняется puts sometimes first, emphasizing the frequency a little more

Иногда is an adverb meaning sometimes. In Russian, adverbs are fairly flexible in position.

All of these can work, depending on emphasis:

• Судьба иногда меняется.
• Иногда судьба меняется.
• Судьба меняется иногда. (less neutral in many contexts, but possible)

The version you have is a very natural neutral order.

The stress is:

• судьбá
• иногдá
• меня́ется

A rough pronunciation guide:

• sood'-BA inag-DA min-YA-yet-sa

A more careful note:

• судьба has a soft consonant before ь
• я in меняется sounds like ya
• -ется / -ется is often pronounced a bit more smoothly in normal speech than it looks in spelling

Usually it sounds like a general statement:

• Fate sometimes changes.

Because of иногда, the sentence describes something that happens from time to time, not necessarily right at this moment.

Russian present tense often covers both:

• general truths
• repeated actions
• actions happening now

Here, the most natural interpretation is a general or repeated situation.

Yes. Both fate and destiny are common translations of судьба.

Which one sounds better depends on style:

• fate often sounds a bit more neutral or common
• destiny can sound a bit more literary or philosophical

In many learning contexts, either is acceptable.