Mi volas gajni pli da mono, sed mi ne volas elspezi la tutan monon en unu semajno.

Because -i is the Esperanto infinitive, the form that corresponds to English to earn or to spend.

After a verb like volas (want), Esperanto normally uses the infinitive directly:

• Mi volas gajni = I want to earn
• Mi ne volas elspezi = I do not want to spend

So Esperanto does not need a separate word like English to here.

Because pli is a quantity word here, and Esperanto usually uses da after quantity expressions before a noun.

So:

• pli da mono = more money
• multe da mono = a lot of money
• iom da mono = some money

This is especially common with things treated as an amount rather than as separate countable items. Since mono is normally treated like a mass noun, pli da mono is the natural form.

Because after da, the noun normally stays in its basic form.

So even though the whole idea pli da mono is the object of gajni, the noun after da remains:

• pli da mono, not pli da monon

This is a very common pattern in Esperanto:

• Mi havas multe da laboro
• Ŝi trinkas iom da akvo
• Ni bezonas pli da tempo

Because in la tutan monon, mono is directly the object of elspezi, so it takes the accusative -n.

• elspezi monon = to spend money
• elspezi la tutan monon = to spend all the money

Here there is no da phrase blocking the accusative on the noun itself, so monon is correct.

Because tutan is an adjective describing monon, and adjectives must agree with the noun in Esperanto.

Since monon is:

• singular
• accusative

the adjective must match it:

• la tutan monon

Compare:

• la tuta mono = the whole amount of money / all the money, as a subject or non-object
• mi elspezis la tutan monon = I spent all the money

So the -n appears on both the noun and its adjective.

The prefix el- often gives the idea of out or completely out.

So elspezi suggests spending something out, using it up.

In this sentence, that fits well:

• ne volas elspezi la tutan monon = does not want to spend all the money up

Even if a learner first thinks of elspezi simply as spend, the idea of using up is often present.

Because en unu semajno usually means within one week or in the course of one week.

That is slightly different from dum unu semajno, which means for one week or throughout one week.

So:

• elspezi la tutan monon en unu semajno = spend all the money within a single week
• elspezi monon dum unu semajno = spend money for one week / over the duration of a week

In this sentence, en unu semajno is the natural choice because the idea is finishing the spending within that time.

Because Esperanto normally states the subject in each clause.

So this is natural:

• Mi volas..., sed mi ne volas...

Even though English sometimes feels similar, Esperanto does not usually drop the second subject just because it is the same as the first one.

Yes, Esperanto word order is fairly flexible, because endings show grammatical roles. But the original order is the most neutral and natural.

For example, these are still understandable:

• Sed mi ne volas elspezi la tutan monon en unu semajno
• Mi volas pli da mono gajni

However, the given sentence sounds smoother and more standard:

• Mi volas gajni pli da mono, sed mi ne volas elspezi la tutan monon en unu semajno.

So a learner should usually start with this basic word order unless there is a reason to emphasize something.

Here it means earn.

Esperanto gajni can cover both ideas, depending on context:

• gajni monon = earn money
• gajni ludon = win a game
• gajni premion = win a prize

So the object often tells you which English word makes the most sense. Here, since the object is mono, earn is the natural translation.