Η μαμά μου βάζει τα ρούχα στο πλυντήριο κάθε Τετάρτη.

In Greek, unstressed possessive pronouns like μου, σου, του, της, μας, σας, τους normally come after the noun, not before it.

• η μαμά μου = my mom
• το βιβλίο σου = your book
• το σπίτι μας = our house

Putting μου before the noun (e.g. μου μαμά) is not standard modern Greek and sounds wrong in this context.

Η is the definite article for feminine, singular, nominative nouns.

• η = the (feminine, singular, subject of the sentence)
• μαμά = mom

So Η μαμά μου literally means The mom of mine, i.e. My mom, and it is the subject of the verb βάζει in this sentence.

βάζω is the verb to put / to place in its dictionary (1st person singular) form.

The present tense conjugation (indicative, active) starts like this:

• εγώ βάζω = I put
• εσύ βάζεις = you (singular) put
• αυτός / αυτή / αυτό βάζει = he / she / it puts

In the sentence, the subject is η μαμά μου = she, so we need the 3rd person singular:

• η μαμά μου βάζει = my mom puts

τα is the definite article for neuter plural in the accusative case (object form).

• τα ρούχα = the clothes

Here, τα ρούχα are the direct object of the verb βάζει (what does she put? the clothes), so Greek uses the accusative form with τα.

Three hints:

1. The article τα is neuter plural.
2. The noun ρούχο (singular) becomes ρούχα in the plural.
3. Semantically, clothes in English is also plural.

So:

• το ρούχο = the item of clothing
• τα ρούχα = the clothes

στο is a contraction of:

• σε (in, at, to) + το (the, neuter singular)

So:

• σε το πλυντήριο → στο πλυντήριο = in the washing machine / into the washing machine

This contraction is very common:

• σε + τον → στον
• σε + την → στη(ν)
• σε + το → στο

Most nouns ending in -ο are neuter in modern Greek.

• το πλυντήριο = the washing machine (neuter)
• το βιβλίο = the book (neuter)
• το σπίτι = the house (neuter, ends in -ι but also neuter)

The article το (and in our sentence, στο = σε + το) confirms that πλυντήριο is neuter singular.

κάθε means every / each and it normally goes without an article before days of the week or repeated time units:

• κάθε Τετάρτη = every Wednesday
• κάθε μέρα = every day
• κάθε μήνα = every month

So you do not say *η κάθε Τετάρτη in this meaning of every Wednesday in a routine.

Days of the week in Greek are written with a capital letter, just like in English:

• Δευτέρα = Monday
• Τρίτη = Tuesday
• Τετάρτη = Wednesday
• etc.

So κάθε Τετάρτη correctly uses a capital Τ.

Greek present tense (βάζει) usually covers what English expresses with both:

• simple present: she puts
• present continuous: she is putting

In this sentence, with κάθε Τετάρτη, it clearly describes a habitual action:

• Η μαμά μου βάζει τα ρούχα στο πλυντήριο κάθε Τετάρτη.
  = My mom puts the clothes in the washing machine every Wednesday.

So βάζει here means does regularly / habitually.

You could, but the meaning changes slightly:

• βάζει τα ρούχα στο πλυντήριο = she puts the clothes into the washing machine (focus on the physical action of placing them inside).
• πλένει τα ρούχα = she washes the clothes (focus on the action of washing; it could be by machine or by hand).

So the original sentence is more specific about using the machine and the act of putting the clothes in it.

Greek word order is relatively flexible, but there are natural and common patterns.

The most neutral order here is:

• Η μαμά μου βάζει τα ρούχα στο πλυντήριο κάθε Τετάρτη.

You might also hear:

• Κάθε Τετάρτη η μαμά μου βάζει τα ρούχα στο πλυντήριο.
  (Putting emphasis on every Wednesday.)

But you cannot freely separate articles from nouns or move μου in front:

• ✗ μου μαμά βάζει… (incorrect)
• ✗ βάζει η μαμά μου τα ρούχα κάθε Τετάρτη στο πλυντήριο (understandable, but sounds awkward; the original order is more natural).