Eu coloco o travesseiro no sofá.

In European Portuguese, definite articles are normally required before specific nouns.

• o is the masculine singular definite article, so o travesseiro = “the pillow.”
• Dropping the article (just travesseiro) sounds odd in regular speech.
• If you meant “a pillow” (any pillow), you would say um travesseiro instead.

Portuguese contracts certain prepositions with articles:

• em (in/on) + o (the) → no.
• So em o sofá becomes no sofá, which here means “on the sofa.”
• Context tells you whether em means “in” or “on”—here it clearly means “on.”

Both verbs translate as “to put,” but they differ slightly:

• colocar is regular: eu coloco, tu colocas…
• pôr is irregular: eu ponho, tu pões…
• Meaning-wise they’re interchangeable:
  • Eu coloco o travesseiro no sofá.
  • Eu ponho o travesseiro no sofá.
• pôr is a bit more colloquial and shorter; colocar may sound more neutral or formal.

Portuguese is a pro‑drop language: the verb ending -o already indicates eu (“I”).

• You can say simply Coloco o travesseiro no sofá.
• Include Eu only for emphasis or clarity (e.g. contrasting with someone else).

Travesseiro is masculine, so it takes o in the singular.

• As a rule of thumb, most Portuguese nouns ending in -o are masculine.
• There are exceptions, so when in doubt, check a dictionary.

Yes. All three express “on the sofa,” but with minor style differences:

• no sofá (most common, neutral)
• sobre o sofá (slightly more formal or literary)
• em cima do sofá (colloquial, emphasizes “on top”)
  Example: Coloco o travesseiro em cima do sofá.

Yes, Portuguese allows some flexibility for emphasis.

• No sofá, coloco o travesseiro.
  (emphasizes the location)
• Standard neutral order remains Coloco o travesseiro no sofá.

Use the possessive adjective agreeing with travesseiro (masculine singular):

• o meu travesseiro = “my pillow.”
  Full sentence: Eu coloco o meu travesseiro no sofá.