Have several, etc. irons in the fire
Definition 1 of 1
Pro Tip 1/3Metaphorical Use
Understand this phrase is a metaphor, comparing multiple tasks to blacksmithing, where irons are literal metal rods. 
With his startup, blog, and studies, John really has several irons in the fire.
Pro Tip 2/3Risk Implication
This phrase can imply managing risk by not relying on a single opportunity for success. 
She has irons in the fire with job applications to several companies.
Pro Tip 3/3Balance Challenge
Using this phrase suggests a challenge in balancing multiple projects or obligations at once. 
He's studying for exams, writing a novel, and doing an internship – that's a lot of irons in the fire.