Trasferisco le foto sul computer.

Because the verb is trasferire (to transfer), and it belongs to a group of -ire verbs that add -isc- in some present-tense forms.

For trasferire, the present tense goes like this:

• io trasferisco = I transfer
• tu trasferisci = you transfer
• lui/lei trasferisce = he/she transfers
• noi trasferiamo = we transfer
• voi trasferite = you all transfer
• loro trasferiscono = they transfer

So trasferisco is the correct I form.

Italian often leaves out subject pronouns when they are already clear from the verb ending.

• Trasferisco already means I transfer
• So you do not need to say io trasferisco

You can say Io trasferisco le foto sul computer, but normally io is only added for emphasis, contrast, or clarity.

Le is the plural feminine definite article, meaning the.

• singular: la foto = the photo
• plural: le foto = the photos

Even though foto ends in -o, it is actually short for fotografia, which is feminine. So:

• una foto
• la foto
• le foto

Sul is a contraction of:

• su = on, onto, to
• il = the

So:

• su + il = sul

In this sentence, sul computer means something like onto the computer or to the computer, depending on the context.

In Italian, when talking about moving files or photos to a device, su is very common.

• sul computer = onto/to the computer
• nel computer = in the computer

Both can make sense in some contexts, but sul computer is very natural when talking about transferring or saving digital files onto a device.
Nel computer focuses more on being inside the computer.

Yes. In Italian, computer is generally treated as a masculine noun:

• il computer
• sul computer

Many borrowed words in Italian are assigned a grammatical gender, and computer is masculine.

Also, the noun usually stays the same in the plural:

• il computer
• i computer

It is in the present tense, but like the English present, it can have more than one use depending on context.

It can mean:

• I transfer the photos onto the computer
• I am transferring the photos onto the computer
• I usually transfer the photos onto the computer

Italian present tense often covers both the simple present and the present progressive, unless the speaker wants to be more explicit.

If you want to emphasize right now, Italian can also say:

• Sto trasferendo le foto sul computer = I am transferring the photos onto the computer

The normal, neutral word order is:

• Trasferisco le foto sul computer.

That is:

• verb: Trasferisco
• object: le foto
• prepositional phrase: sul computer

Italian word order is fairly flexible, but changing it usually changes the emphasis.

For example:

• Le foto le trasferisco sul computer.
  = The photos, I transfer them onto the computer.

That sounds more marked or emphatic. The original sentence is the most standard version.

It is pronounced roughly like:

• tras-feh-REE-sko

The stress is on ri:

• tras-fe-RÍ-sco

A rough pronunciation guide for the whole sentence is:

• tras-feh-REE-sko leh FOH-toh sool kom-PYOO-ter

Keep in mind that Italian pronunciation is more regular than English, so once you know the sounds, it is quite predictable.

No. The correct verb form is trasferisco.

• Trasfero is not standard Italian.
• Transferisco is sometimes heard because of English influence, but the normal Italian verb is trasferire, not transferire.

So the correct sentence is:

• Trasferisco le foto sul computer.