She's really strong from working the farm her whole life.
She's very business-savvy, having forged a partnership with several grocery stores to sell her apples.
Although Applejack now mostly deals with the administrative aspects of running Sweet Apple Acres, she certainly isn't afraid to get her hooves dirty and work the fields.
Since she's now one of the main suppliers of apples and apple-related products in Equestria, she's hired a few farmhands to help take care of the orchards.
Although Big McIntosh was next in line to become the head of Sweet Apple Acres after Granny Smith's passing, he decided to step down and defer the position to Applejack, preferring to continue working the farm and staying out of the spotlight.
Applejack is in a relationship with Rainbow Dash and Trixie Lulamoon, and they have four children together in total. Most of their children live on or around the farm with them.
On that note, Applejack and Trixie got together before both of them started dating Rainbow Dash. Both of them later become aware that Rainbow is attracted to them both, and there's a brief period of romantic tension there before AJ and Trixie decide to approach Dash and propose a triad. Dash enthusiastically agrees (she tries to play it cool at first. It doesn't work) and the three of them start dating.
Even though not all of the trouple's kids are hers biologically, Applejack still loves all her children and views them as her own. She'd always wanted a big family, and even though she never would've expected how everything would turn out, she couldn't be happier with the family she has.
Applejack is probably the closest to Sunny Skies, her and Rainbow Dash's son. The two of them would often wrassle around in the dirt once he started to get big and strong and needed a way to get his energy out; even as an older mare, Applejack can still hold her own against a young stallion.
She's a little less close to Snapdragon and Dazzle Flash, but still has a strong bond with them, even if she doesn't quite get Dazzle's love of pyrotechnics.
She's the least close to Evening Harvest — they butted heads a lot when Eve was a moody teenager and their relationship still isn't the best. Eve is well aware that her mother has a stronger bond with her brother and is kind of resentful of that, feeling like she's the 'lesser' twin. AJ wants to have a better relationship with her daughter, but Eve just pushes her away when she tries to get through to her. Maybe with some time and patience they'll be able to work things out.
She's still as down-to-earth, stubborn, honest, and charitable as ever.