Bitcoin is censorship resistant in the sense that no single entity has the ability to reverse a Bitcoin transaction or blacklist a wallet or address. Any node can broadcast a transaction, and any miner can mine any transaction. Thus, censoring a Bitcoin transaction is virtually impossible.
When a Bitcoin transaction is submitted to the network, it is relayed from node to node until it has reached most nodes. These nodes keep unconfirmed transactions in a database called the mempool, and miners gather transactions from the mempool to build the blocks they attempt to add to the chain. When a miner mines a block with a transaction in it, that transaction is removed from the mempool and is considered confirmed.
This process has relatively few chokepoints. As long as an individual can reach a node on the Bitcoin network, they can broadcast a transaction and trust that it will be confirmed. In order to preempt the attempts of governments or other large organizations to censor transactions, Bitcoin developers have engineered many unique ways of broadcasting transactions, including over mesh networks, satellites, and HAM radio.