1) As in English, there are subject personal pronouns in Portuguese: 1st person singular: "EU" 2nd person singular: "TU" 3rd person singular: "ELE" 1st person plural: "NÓS" 2nd person plural: "VÓS" 3rd person plural: "ELES/ELAS" Also, there is the pronoun "VOCÊ"/"VOCÊS" that means "you" BUT... it is treated as third-person... Just remember that both mean "you" in English, but "TU" is treated as second-person and "VOCÊ" is treated as third-person. Ok? 2) "TEU" and "SEU" are possessive pronouns and they are related to the subject personal pronouns indicated above at point 1. They both mean "your"/"yours" in English. BUT... "TEU" is related to the second-person in singular only "SEU" is related to the third-person in singular and plural 3) Now let's see some examples of using "TEU" e "SEU"... - "TU tens um carro" (You have a car) - "Então, o carro é TEU." (So the car is yours) - "VOCÊ tem um carro" (You have a car) - "Então o carro é SEU" (So the car is yours) In Portugal/Angola/Moçambique people use "TU" to talk with friends and use "VOCÊ" to show respect (talking to older people, authorities etc). In some parts of Brasil (North and South) people prefer to use "TU" always. And in some parts of Brasil (midle regions) people prefer to use "VOCÊ" always. 4) And what about Their(s), Your(s), Her(s), His, Its in Portuguese?? The correct is to use "SEU", but the possessive pronouns SEU/SEUS/SUA/SUAS can cause ambiguities, because you don’t know if the pronoun is referring to "you" (VOCÊ) or "he/she" (ELE/ELA). To avoid ambiguities you can use DELE/DELA/DELES/DELAS. Examples: "Ele não encontrou seu amigo." it can be translated as "He did not meet your friend." or "He did not meet his friend." So you can use "Ele não encontrou o amigo dele." to make it clear that you are saying "He did not meet his friend."

it's nothing but differences between two dialects: Brazilian and European Portuguese. in Brazil the pronoun 'tu' was forgotten being replaced by 'você'. then, it also happened with possessive pronouns. nobody says 'teu\tua' anymore, we say 'seu\sua', originally third persons pronouns. his is 'dele' and her is 'dela'. for example Brazil: você caminha com o SEU cachorro. Portugal: tu caminhas com o TEU cachorro. English: you walk with your dog Brazil: o homem tirou a camisa DELE Portugal: o homem tirou a SUA camisa English: the man took his t-shirt off their is deles\delas in Brazil and seus\suas em Portugal. about you (plural) it's again a regional difference. in Portugal, they say 'vosso\vossa'. in Brazil it's always 'de vocês' no matter the gender seu = masculine gender sua = feminine gender I hope I answered your question