Just to understand if i've understood well, the main purpose of this coin is to create a blockchain with a througput times and times better than the other blockchain?
You understood correctly. The first high-throughput public blockchain platform designed to scale to thousands of transactions per second. It brings the theory of sharding to practice with its novel protocol that increases transaction rates as its network expands.
Sharding - splitting large data into parts (fragments) by certain attributes and algorithms in order to significantly speed up access to the desired data.
What about "what is the ZIL token for?":
This token grants holders the right to use the platform, payment for sending transactions, as well as performing intellectual contracts. Zilliqa has a final offer volume of 21 billion tokens.