No metemos la geocoin en el microcaché.

Because Spanish usually makes a sentence negative by putting no directly before the conjugated verb.

• Metemos = we put / we are putting
• No metemos = we do not put / we are not putting

Unlike English, Spanish does not need a separate helping verb like do.

Metemos is the 1st person plural form of meter, so it means we put or we are putting.

Spanish often leaves out the subject pronoun when the verb ending already shows who the subject is. So:

• No metemos la geocoin...
• Nosotros no metemos la geocoin...

Both are possible, but the version without nosotros is more natural unless you want emphasis.

Metemos is the present indicative of meter.

In English, the Spanish present tense can often translate in more than one way depending on context:

• we put
• we are putting
• sometimes even we do put

So No metemos la geocoin en el microcaché could mean either We don’t put the geocoin in the microcache or We’re not putting the geocoin in the microcache, depending on the situation.

Both verbs can sometimes be translated as to put, but they are not exactly the same.

• meter often suggests putting something into/inside something
• poner is more general: to place / to put

Because a microcaché is a small container, meter sounds very natural here: you are putting something inside it.

So:

• meter la geocoin en el microcaché = put the geocoin into the microcache

La is the direct object article here, and it shows that geocoin is being treated as a feminine singular noun.

Loanwords in Spanish are given grammatical gender, and in geocaching usage geocoin is commonly treated as feminine, probably by association with words like moneda.

So:

• la geocoin = the geocoin

Because la geocoin is a direct object, and it is a thing, not a person.

Spanish uses the personal a mainly with specific people (and sometimes pets or personified beings), not normally with objects.

So:

• Veo a María = I see María
• Metemos la geocoin = We put the geocoin

No a is needed here.

Because en + el does not contract in Spanish.

Only these two common contractions happen:

• a + el = al
• de + el = del

But:

• en + el = en el

So en el microcaché is correct.

Yes. In English, we often distinguish between:

• in = location
• into = movement to the inside

Spanish often uses en in places where English would use either in or into, especially with verbs like meter that already imply movement inward.

So:

• meter algo en algo = to put something into something

The idea of movement is carried mainly by meter, not by a special preposition.

No. No metemos... is normally a statement, not a command.

It means something like:

• We don’t put...
• We’re not putting...

If you wanted Let’s not put..., Spanish would usually use the subjunctive:

• No metamos la geocoin en el microcaché. = Let’s not put the geocoin in the microcache.

That is an important difference:

• No metemos = statement
• No metamos = negative suggestion/command for we

The accent mark shows where the stress goes: micro-ca-CHÉ.

In Spanish spelling, a word ending in a vowel, n, or s is normally stressed on the second-to-last syllable. Since this word is stressed on the last syllable, it needs a written accent.

So the accent helps show the intended pronunciation of this adapted form in Spanish.

Here it is masculine, which is why the sentence has el microcaché.

So:

• el microcaché
• en el microcaché

That gender is just something you learn with the noun, like with many borrowed or specialized words.