I didn't understand this point. What is mixing service platforms?

Bitcoin tumbling (mixing) involves the usage of a third party service to break the connection between a wallet address sending coins and the addresses receiving coins. So if a person does not wish the whole world to know from where they got their coins, and/or to which addresses the Bitcoins are sent, then tumbling is the way to go. A provider of Bitcoin tumbling service is referred to as Bitcoin tumbler.

Coin mixing will provide you with a certain amount of privacy, by mixing your coins with other coins previously sent or in their reserve and sending different coins to the address you specify. When looking at the blockchain, one will be able to see you sent your coins to a wallet. And that someone sent coins to the wallet you want them sent, there will be no connection between your wallet address and the one where you want your crypto delivered.