Taken directly from the www.irs.gov website:
Generally, U.S. citizens and resident aliens who are not eligible to be claimed as a dependent on someone else’s income tax return are eligible for this second payment. Eligible individuals will automatically receive an Economic Impact Payment of up to $600 for individuals or $1,200 for married couples and up to $600 for each qualifying child. Generally, if you have adjusted gross income for 2019 up to $75,000 for individuals and up to $150,000 for married couples filing joint returns and surviving spouses, you will receive the full amount of the second payment. For filers with income above those amounts, the payment amount is reduced.
To get more info about it, check out “Treasury and IRS begin delivering a second round of Economic Impact Payments to millions of Americans“.