Alla cassa la cassiera sorride e mi dà lo scontrino.

Because alla cassa sets the scene first: at the checkout / at the cash register.

Italian often puts a place or time expression at the beginning of the sentence when it gives useful context. It is a very natural order:

Alla cassa, la cassiera sorride e mi dà lo scontrino.

It does not change the basic meaning; it just frames the action as happening there.

Alla is a contraction of a + la.

• a = to / at
• la = the for a feminine singular noun

Since cassa is feminine singular, a la cassa becomes alla cassa.

This is the same pattern as:

• al = a + il
• allo = a + lo
• alla = a + la
• ai = a + i
• agli = a + gli
• alle = a + le

They are related, but they are not the same word.

• cassa = the cash register, checkout, or till
• cassiera = the female cashier

So in this sentence:

• Alla cassa = at the checkout
• la cassiera = the cashier

A masculine form also exists:

• cassiere = male cashier

Because cassiera is a noun, and Italian usually uses the definite article where English often does too, and sometimes even where English would omit it.

Here la cassiera means the cashier.

Italian likes articles with professions or roles when referring to a specific person in context. Since we are clearly talking about the cashier at the checkout, la cassiera is the natural choice.

Sorride is the third-person singular present indicative of sorridere.

So:

• io sorrido = I smile
• tu sorridi = you smile
• lui/lei sorride = he/she smiles
• noi sorridiamo = we smile
• voi sorridete = you all smile
• loro sorridono = they smile

Here the subject is la cassiera, which is singular, so the verb is sorride.

Mi means to me.

It is an indirect object pronoun, and in Italian these short pronouns usually go before a conjugated verb.

So:

• mi dà = gives me / gives to me

Compare:

• mi parla = speaks to me
• mi scrive = writes to me
• mi dà lo scontrino = gives me the receipt

Italian normally prefers mi dà rather than dà a me, unless you want special emphasis.

The accent helps distinguish the verb dà from the preposition da.

• dà = he/she gives
• da = from, by, at, depending on context

So in this sentence, dà is from the verb dare.

Examples:

• mi dà lo scontrino = she gives me the receipt
• vengo da Roma = I come from Rome

Because scontrino begins with s + consonant.

In Italian, masculine singular nouns usually take:

• il before most consonant sounds
• lo before certain special sound groups, including s + consonant

Since scontrino starts with sc and that counts here as s + consonant, the correct article is lo.

Examples:

• lo scontrino
• lo studente
• lo specchio
• lo zaino

But:

• il libro
• il tavolo

The plural of lo scontrino is gli scontrini.

Italian word order is flexible, but not all versions sound equally natural.

This sentence is very natural:

Alla cassa la cassiera sorride e mi dà lo scontrino.

You could also say:

La cassiera sorride e mi dà lo scontrino.

if the location is already understood.

If you move alla cassa, the emphasis changes a bit. Putting it first makes it sound like scene-setting information. That is probably why it comes first here.

So the order is not completely fixed, but this version is a very natural one.

Because Italian usually does not need subject pronouns when the subject is already clear.

Here the subject is explicitly stated as la cassiera, so adding lei would be unnecessary:

• la cassiera sorride = the cashier smiles

Italian often omits subject pronouns even when there is no noun, because the verb ending already tells you the person:

• sorrido = I smile
• sorride = he/she smiles

A rough guide for an English speaker:

• cassa ≈ KAS-sa
• cassiera ≈ kas-SYE-ra
• scontrino ≈ skon-TREE-no

A few useful pronunciation notes:

• In cassa, the c before a sounds like k
• The double ss is pronounced more strongly than a single s
• In scontrino, the beginning sc here sounds like sk, not like English sh
• Stress falls on:
  • càs-sa
  • cas-siè-ra
  • scon-trì-no

These sound details matter in Italian more than they usually do in English.