In Dragon Ball Z canon, Frieza does not have a son... but not every Dragon Ball manga is canon. After Dragon Ball GT (temporarily) closed the book on Goku and friends and before Dragon Ball Super brought Frieza back from the dead for another rematch against Goku, there was Neko Majin Z. Neko Majin Z was a parody manga written and illustrated by Akira Toriyama about a cat-like alien confronting Vegeta and Goku.
In the first chapter of Neko Majin Z, Neko Majin Z fights a Saiyan named Lord Onio. In the second chapter of Neko Majin Z, Lord Onio returns with Kuriza, who Onio insists is the strongest in the universe. Kuriza is the son of Frieza and grandson of King Cold. Since appearing in this non-canon manga, Kuriza has made multiple appearances outside Neko Majin Z, including in video games. So who is Kuriza, and why should Frieza's son be a canon part of Dragon Ball Z lore?
Who is Kuriza, Son of Frieza?
In Neko Majin Z, Kuriza comes to Earth to fight Neko, but the manga runs out of pages before Kuriza's full power is unleashed. After that, he just hangs out with Neko, fighting him off-screen and rooting against him when new enemies -- like Vegeta -- show up to fight him.
Kuriza's name, much like the rest of his family, is a pun. However, rather than a cold pun, his name is actually a pun on nuts since his head is shaped like an upside-down chestnut. Kuriza has all the powers of Frieza but lacks the responsibilities or evil. Kuriza seems to lack an army or squad of soldiers, but also seems far more childish and less malignant. While he roots against Neko, he doesn't seem interested in seeing him killed, seeming content to play games with him instead. That said, when Vegeta comes, Kuriza gets excited, since he knows his father must've sent Vegeta to "save" him.
Kuriza in the Video Games
Despite being a non-canon character, Kuriza has appeared in three separate video games. His first appearance was in Dragon Ball Z: Budokai 2. He exclusively appears in the Japanese version as an alternate costume for Frieza. He later appears as a playable character in Dragon Ball Heroes, both in his first and final forms.
Kuriza is only shown to deal in the family business during his appearance in Super Dragon Ball Heroes: World Mission, an anomaly occurs that allows Frieza and King Cold to gain an edge during the fight with Trunks. This leads to the player fighting against the Frieza clan. Kuriza arrives to defend his father, arriving around the same time as his Uncle Cooler, Cooler's Armored Squadron and Aka from "Yo! Son Goku and His Friends Return!!" They fight the heroes as part of the overall forces of the Frieza Clan.
It's in World Mission that we learn more about Kuriza. Despite being Frieza's son, Kuriza is far closer to his Uncle Cooler, who seems to validate his nephew's desire to fight. Kuriza seems eager to prove himself to his more powerful relatives, as though aware that, as Frieza's more innocent son, he's far less intimidating than the rest.
Why Kuriza Should Be Canon
Kuriza probably cannot fit into the modern canon without his character being altered somewhat. However, he's a unique addition to the Frieza clan. He isn't an evil warlord like Frieza and King Cold, nor a practical yet cold warrior like Cooler. He's a kid who grew up around his evil relatives but, try as he might, just can't quite be as evil as his dad.
He exists as a great foil to Frieza, as someone who is just as dangerous but lacks the malice to inflict harm on others in the same way. That makes him an interesting character, especially if you take in the dynamic from Super Dragon Ball Heroes into account. Kuriza is not canon at all, but still is a unique addition to the Frieza Clan that at the very least deserves more development in non-canon media, if not a full-blown Dragon Ball Super canon rebirth a la Broly.