Jessica Biel and Justin Timberlake welcomed their second child, a son named Phineas, last summer
jessica biel

Jessica Biel is opening up about the adorable relationship between her two sons.

During a new episode of The Ellen DeGeneres Show, airing Monday, the actress revealed that her sons Phineas and Silas, whom she shares with husband Justin Timberlake, can't get enough of one another.

Asked whether the two little boys get along, Biel, 39, explained that Phineas, who the couple welcomed last summer, and Silas, 6, "both think the other one is hilarious."

"Silas, he is the performer, he wants to make the jokes and he wants the whole attention on him, so Phin only has eyes for him," The Sinner star said.

"Everything Silas does is hilarious and anything Phin does is hilarious, so they just laugh at each other all day long," she continued. "It's so cute."

Speaking about being a mom of two, Biel said it's been a "wild, crazy, fun ride" thus far.

"A very wise friend of mine said, 'One is a lot, and two is a thousand.' And I said 'Oh my god, you're right,' " she told host Ellen DeGeneres. "That's exactly how it feels. You're just man-on-man defense, one person's over here and the other person's over here."

Jessica Biel and Justin Timberlake
Jessica Biel and Justin Timberlake with son Silas
| Credit: Justin Timberlake/Instagram

Biel also dished on her and Timberlake's rocky experience with sleep training.

"We started to sleep train and [Phineas] was doing so great, and then all of his teeth started to come in and now nobody is sleeping again," Biel shared. "But he's so cute and I think that's why they're so cute is because you just look at them and you're like, 'I'm so tired, but you're so cute and I love you and I'm gonna be okay with this somehow.' "

The actress admitted that it's "so hard" to let her son cry "even for a few minutes."

"That's kind of the sleep training we were doing, you just let them go for a couple of minutes and then you go in and go, 'You're good, you're fine,' " she explained.

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While Biel said that their youngest son "did a beautiful job" with sleep training, the couple "never really followed through with Silas."

"I think it was also first child we were nervous, and now we're just like, 'You're gonna be fine, you're gonna make it, you'll be okay,' " she said with a laugh.

In January, Timberlake confirmed he and Biel welcomed a second child during an episode of The Ellen DeGeneres Show.

"He's awesome and so cute," Timberlake said of the couple's new addition. "Nobody's sleeping, but we're thrilled. We're thrilled and couldn't be happier. Very grateful."