Understanding private keys, public keys, adresses and transactions I need some claryfication about the things, here it goes:
1. For what I've read, for generate a bitcoin address is following this flow:(General speaking) Private Key (SK) -> Public Key (PK) -> Address (A). Some say that SK -> PK == A. Which one is correct?
2. Now, in a transaction when X to Y of "n" bitcoins happens this: X signs (digitally) the transaction "t" with its SK and this the part that I don't get it. How "Y" does to open and verify that the transaction was send from X? or besides that X signs the transaction he encrypts? the transaction again with the PK/A of Y for Y can open it? There's something that I missing?

Note that my native language it's not english and it's hard for me to understand this complex topic.

Thanks in advance
Private Key (SK) -> Public Key (PK) -> Address (A). Some say that SK -> PK == A. Which one is correct?


The first one. An address is not a public key. It is some encoding (Base 58 Check encoding or Bech32, depending on the address type) of the RIPEMD160 hash of the SHA256 hash of the public key. The address comes from the public key, but it is not the public key itself. A public key can have multiple addresses.


  
  Now, in a transaction when X to Y of "n" bitcoins happens this: X signs (digitally) the transaction "t" with its SK and this the part that I don't get it. How "Y" does to open and verify that the transaction was send from X? or besides that X signs the transaction he encrypts? the transaction again with the PK/A of Y for Y can open it? There's something that I missing?
  


Signing is not the same thing as encrypting. Transactions are not encrypted, no data in a transaction is secret. It can all be read by everyone.

A digital signature can be verified by knowing the message that was signed and the public key corresponding to the private key that signed the message. In the case of Bitcoin, the message is defined by the consensus rules (it is the hash of certain parts of the transaction), and the public key is provided in the transaction itself. Those three things (the public key, signature, and message) can then be used to verify that the signature is valid.