tempmute.js

// If the command is like: -tempMute <mention> <minutes> [reason]
exports.run = (client, message, [mention, minutes, ...reason]) => {
  // You need to parse those arguments, I'll leave that to you

  // This is the role you want to assign to the user
  let mutedRole = message.guild.roles.find(role => role.name == "Muted");
  // This is the member you want to mute
  let member = message.mentions.members.first();

  // Mute the user
  member.addRole(mutedRole, `Muted by ${message.author.tag} for ${minutes} minutes. Reason: ${reason}`);

  // Unmute them after x minutes
  setTimeout(() => {
    member.removeRole(mutedRole, `Temporary mute expired.`);
  }, minutes * 60000);
};