You send: Avalanche (Binance Smart Chain)
AVAX is the native asset of Avalanche, whose C-Chain is Ethereum-compatible: the same 0x addresses and wallets, with fees paid in AVAX. Transactions reach finality in about a second. More about Avalanche.
On this pair it moves over BEP20 — an address there starts with 0x — 42 characters.
AVAX also exists on other networks — different addresses, not interchangeable: C-Chain, X-Chain.