If you reach your daily limit, all ad groups in the campaign are paused. Here are the details:
Daily - Standard: This budget will be used by this campaign only.
It's important to note that your daily limit is a target -- your actual spend might be higher or lower. Variations are caused by a number of factors, such as different traffic volumes in different days of the week, or automatic detection and refunding of fraud clicks that can give money back to a campaign within a few hours of the click. Microsoft Advertising anticipates and automatically compensates for the fluctuations, and usually keeps overspend to less than 100% above your daily limit.
If you don't take action to resume the campaign in Budget paused status, the campaign automatically restarts at the beginning of the next month.
Find calculations to convert your daily budget to a monthly budget, find the remainder of your budget for the month, and learn more about choosing a budget type at: What are my budget options?