Translate a Trading Card Game's Decklist Shorthand for a Friend Learning to Read One

A decklist looks like a shopping list crossed with a maths exam: quantities, abbreviations, a sideboard nobody has explained. A friend picks up the game and stares blankly at the sheet you handed over. This turns the shorthand into one plain paragraph explaining what the deck actually does.

Translate a trading card game decklist for someone who has never read one before. The decklist is: [paste decklist, for example 4x Lightning Bolt, 2x Counterspell, 1x sideboard]. Explain what the quantity numbers mean, what abbreviations like sideboard, mainboard or mana curve refer to, and what the deck is trying to do overall in one paragraph. Write for someone who knows the game's basic rules but has never looked at a competitive decklist. Keep the whole explanation under 200 words and avoid introducing any jargon you have not already defined in the same answer.