robotto ga hako wo hakobu.

They are particles, which show the role of each noun in the sentence.

• ロボット が = the robot is the subject, the thing doing the action
• 箱 を = the box is the direct object, the thing being carried

So in ロボット が 箱 を 運ぶ, が marks who does it, and を marks what is acted on.

Japanese sentences normally put the main verb at the end.

So instead of English The robot carries the box, Japanese is structured more like:

• Robot
  • subject marker
• box
  • object marker
• carry

That is very normal in Japanese. A basic pattern is:

Subject + Object + Verb

So ロボット が 箱 を 運ぶ follows a very standard Japanese word order.

運ぶ is the dictionary form of the verb. It is also the plain non-past form.

That means it can express:

• a present action in a general sense: carries
• a future action: will carry
• a habitual action: carries regularly

By itself, it does not specifically mean is carrying right now.
If you wanted that ongoing meaning, you would usually use 運んでいる.

Both can mark something like the topic/subject area of the sentence, but they are not the same.

• が highlights the grammatical subject: the robot is the one that carries the box
• は marks the topic: as for the robot, it carries the box

So:

• ロボット が 箱 を 運ぶ sounds like you are identifying the robot as the doer
• ロボット は 箱 を 運ぶ sounds more like you are talking about the robot as your topic, perhaps in contrast with something else

For a simple standalone sentence, が is perfectly natural.

Japanese usually does not use articles like English a or the.

So 箱 can mean:

• a box
• the box
• sometimes even boxes, depending on context

Likewise, ロボット can mean:

• a robot
• the robot
• sometimes robots

Japanese often leaves that information to context instead of marking it directly every time.

Japanese uses several writing systems together.

• ロボット is in katakana because it is a loanword, from robot
• 箱 is in kanji, the standard way to write box
• 運ぶ is a mix:
  • 運 is the kanji carrying the main meaning
  • ぶ is hiragana, part of the verb ending

This mix is completely normal in Japanese writing.

The particle を is pronounced o, not wo in normal modern Japanese.

So:

• 箱 を is pronounced roughly hako o

Even though the character is written を, its usual pronunciation as a particle is just o.

Japanese word order is more flexible than English, because particles show each word’s role.

For example, these can still be understood:

• ロボットが箱を運ぶ
• 箱をロボットが運ぶ

because が still marks the subject and を still marks the object.

However, the most neutral and common order is:

ロボット が 箱 を 運ぶ

Changing the order can add emphasis or sound more marked, so beginners should usually stick to the basic pattern first.

They are probably there for learning purposes.

In normal Japanese writing, this sentence would usually be written without spaces:

ロボットが箱を運ぶ。

Japanese does not normally use spaces between words the way English does. Textbooks and beginner materials often add spaces to make the structure easier to see.

Not exactly.

• 運ぶ means to carry / transport / move something from one place to another
• 持つ means to hold / have / carry on one’s person

So if a robot is moving a box somewhere, 運ぶ is a very good choice.
It focuses more on transporting the box, not just physically holding it.

For example:

• 箱を持つ = hold the box
• 箱を運ぶ = carry the box somewhere / transport the box