While Dragon Ball Z saw Goku and the Z Fighters significantly upgrade their powers and strength to take on even bigger threats, the scope escalated considerably in the anime/manga series' second storyline "The Namek" saga. Catapulting the Dragon Ball franchise to interstellar heights, the storyline featured the Z Fighters taking on Frieza and his army in a race to recover the Namekian Dragon Balls and save the universe. While Goku didn't arrive on Namek until the Z Fighters were at the complete mercy of the Ginyu Force, he not only appeared exponentially stronger than he had at the start of DBZ but also possessed a surprising ability that he hasn't utilized since: telepathy.
Goku traveled to Namek separately, taking some time to recuperate from his brutal battle against Vegeta at the end of the preceding Saiyan Saga. In a specially designed spaceship, Goku trained in twenty times Earth's gravity to augment his strength and speed, arriving on Namek in the nick of time to save his friends from the villainous Recoome of Frieza's elite Ginyu Force. After healing Gohan and Krillin from the grievous injuries they endured fighting against Recoome, Goku read Krillin's mind to learn everything that occurred on Namek while he was in transit, including that Vegeta had become a tacit ally against a mutual enemy, giving his old enemy a Senzu bean to heal him after being brought up to speed by the telepathic power.
In order to read Krillin's mind, Goku instructed his best friend to calm himself and quietly touched Krillin's forehead to access his memories. When asked about this by Krillin, Goku admitted he had no idea if this new ability would actually work but intuitively knew that he would be able to access Krillin's mind. Goku also doesn't know how he gained this ability, dismissing it as an added benefit from training diligently at twenty times Earth's gravity in the English-language dub of DBZ, and not providing a reason in the original manga series at all.
Goku's telepathy on Namek is not the first time that telepathic powers have been introduced in Dragon Ball and forgotten just as quickly, with the character in question never to visibly use it again. During the 21st World Martial Arts Tournament in Dragon Ball, a disguised Master Roshi is able to read the mind of Goku's opponent Nam, without coming into physical contact with him, to learn why exactly he had entered the tournament. Neither Roshi nor Goku have utilized their telepathic powers to date, with the instances little more than convenient plot devices to reveal backstories or quickly catch up characters on the plot progression they had missed.
The idea that Goku gained the ability to read minds after training at twenty times Earth's gravity suggests that many of the Z Fighters would similarly possess a degree of telepathy after training under the same conditions if they could use clear their mind and trust their natural instincts. Piccolo has more consistently displayed telepathy, although not so much as a result of his martial arts training but instead derived from his natural Namekian physiology, while Kais are similarly capable of telepathic feats.
With Goku and Vegeta now training with the gods themselves, it's likely that their Super Saiyan God forms could also bring heightened telepathy, with Ultra Instinct's supreme defensive capabilities perhaps informed by it. However, Goku largely acts as if he's forgotten he's one of Dragon Ball's rare telepaths.
