The 35-year-old actress has Silas, two, with husband Justin Timberlake, reported Femalefirst.
"He is a total weirdo. But he's amazing. [Kids are] all weird. They're like these little lovely, strange, mini humans, and they're so specific," Biel said.
"The Sinner" actress also admitted that she struggles to balance her career with raising a child but acknowledged that it is something every parent goes through.
"It's hard - trying to find a balance between work and family and just being an independent human. You're stretched thin everywhere, and it's been amazing creatively but really hard. I think every working parent must feel the same.