Online in Mass Effect Andromeda is covered on this page. The game will feature online elements in both the single player story campaign and Multiplayer.
In single player, you will encounter some Missions that you can send a team to complete or you can tackle them in Multiplayer with other players. Playing in multiplayer however is not a requirement for defeating the single player story.
Multiplayer is a cooperative game mode in which you will team up with other players to complete objectives. As you progress you can unlock new gear and skills for your character to customize your loadout. The mode will allow you to earn a specific currency to buy blind packs to unlock gear at random. There will also be a rotating loot vendor, similar to Xur in Destiny where you can spend earned Mission Funds and real money.