A Discord server needs two server boosts to reach Level 1.
Server Boosts are recurring upgrades that members apply to a particular server. Once two boosts are maintained, Level 1 perks become available, including additional emoji capacity, more sticker slots, improved voice audio quality, an animated server icon, and enhanced streaming options. The boosts are attached to the server rather than permanently owned by one member.
The progression is not one boost per level. Discord’s current standard thresholds are two boosts for Level 1, seven for Level 2, and 14 for Level 3. That is why guesses such as three or five often arise: those numbers may relate to older explanations, other perks, or the number of boosts still needed after some have already been applied.