class WelcomeController < ApplicationController

  def index
  	if logged_in?
  	  @user = current_user
      @invitation = Invitation.new
      @active_invitations = @user.received_invitations.where(seen: false).pluck('DISTINCT sender_id').map{|sender_id| Invitation.find_by(recipient_id: @user.id, sender_id: sender_id) }.reverse
  	  @available_users = User.all.includes(:level, :country, :native_language, :study_language)
  	else
	  	@user = User.new
  	end
  end

end

class WelcomeController < ApplicationController

  def index
  	if logged_in?
  	  @user = current_user
      @invitation = Invitation.new
      @active_invitations = @user.received_invitations.where(seen: false).pluck('DISTINCT sender_id').map{|sender_id| Invitation.find_by(recipient_id: @user.id, sender_id: sender_id) }.reverse
  	  # @available_users = User.all.includes(:level, :country, :native_language, :study_language)
     @available_users =  User.all.includes(:level, :country, :native_language,
      :study_language).where("last_seen_at > ? and id != ?", 10.minutes.ago, current_user.id)
  	else
	  	@user = User.new
  	end
  end

end

Update available users to show only available users that are not the current user
Update available users to show only available users that are not the current user
