Learn Hardcore Polish: Mój komputer pokazuje pogodę: chmury i lekki śnieg. - My computer shows the weather: clouds and light snow.

Because in Polish the verb pokazywać (to show) takes a direct object in the accusative case. Pogoda is a feminine noun whose accusative singular is formed by changing -a to -ę, hence pogodę.

Why isn’t there a dative pronoun mi (as in “pokazuje mi pogodę”)?

Polish allows omitting the dative pronoun when it’s clear from context. You could say Mój komputer pokazuje mi pogodę, but the mi (“to me”) is optional and often dropped for brevity.

Why is chmury spelled like the nominative plural and not chmur (genitive)?

Here chmury and lekki śnieg are still direct objects of pokazuje. Both chmury (feminine plural) and śnieg (masculine singular inanimate) have accusative forms identical to their nominative forms. The genitive plural of chmura would be chmur, but we need accusative plural, so it remains chmury.

Why does the adjective lekki end in -i and not -a or -ie?

Adjectives in Polish agree with their noun in gender, number and case. Śnieg is masculine singular inanimate and in the accusative case it looks like the nominative. The matching masculine singular form of lekki ends in -i (or -y), so we get lekki śnieg.

Why is it mój komputer and not moje komputer or moja komputer?

Possessive pronouns (mój, twój, jego etc.) must match the gender, number and case of the noun they modify. Komputer is masculine singular, so the correct form is mój. Moja would be feminine, moje neuter.

What is the function of the colon : here? Could I use a comma or dash instead?

The colon introduces an explanation or list of items—in this case, the weather elements. You could use a dash (–) informally, or a comma, but the colon is the clearest way to signal “now I’m listing what the weather shows.”

Can I replace pokazuje with wyświetla? Is there a nuance?

Yes. Pokazuje means “shows” in a general sense. Wyświetla (“displays”) is more technical, implying a screen or monitor. So Mój komputer wyświetla pogodę emphasizes the on-screen display, whereas pokazuje is perfectly natural in everyday speech.

Can I switch the order to lekki śnieg i chmury or omit the i when listing?

You can swap the items—lekki śnieg i chmury—without changing meaning. Omitting the i and using a comma (chmury, lekki śnieg) also works as a simple list, but in Polish the coordinating i is very common between the last two items.