Learn Hardcore Portuguese (Brazil): Há muita sujeira no chão da cozinha, então vou pegar a esponja e o rodo. - There is a lot of dirt on the kitchen floor, so I am going to get the sponge and the squeegee.

Breakdown of Há muita sujeira no chão da cozinha, então vou pegar a esponja e o rodo.

Why does the sentence start with há? Does it mean has?

Here há comes from the verb haver, and in this kind of sentence it means there is or there are.

So:

It does not mean has in the English possession sense.

A few useful notes:

há is very common in written Portuguese
in everyday Brazilian speech, people often say tem instead:
- Tem muita sujeira no chão da cozinha
with haver in this meaning, the verb stays in the singular:
- Há muita sujeira
- Há muitas coisas no chão

Why is it muita sujeira and not muito sujeira?

Because sujeira is a feminine singular noun, so muito has to agree with it:

Examples:

Since sujeira is usually an uncountable noun here, Portuguese uses the singular: muita sujeira.