The ads you make for the campaign will appear in people's timelines and in Twitter search — just like Promoted Ads. But when focused on mass awareness, you'll pay for every 1,000 impressions, instead of paying for engagements.
Boosting your presence on Twitter
Tweet impressions are the only thing you pay for. But because the reach objective puts your Twitter presence in the spotlight, you could acquire followers, website visits, likes, and Retweets as well. Because of this, we recommend the reach objective as your "always-on" Twitter solution or the starter campaign for when your goals are more general.
If you want to boost your presence on Twitter, start a campaign with the reach objective. Keep your initial targeting broad (for mass awareness), choose Tweets that best showcase your message, and start talking to a bigger audience.