July in Málaga is basically a packed oven, I'm not gonna lie to you. The heat is brutal, we're talking 35-38 degrees easily, sometimes more, and the humidity from the coast makes everything worse. The beaches are packed, prices go way up, and restaurants are full. That said, if it's your only vacation option then go for it, it's not the end of the world. You gotta go in with the right mindset: wake up early to get to the beach before the crowds arrive, look for beaches further from the center like Rincón de la Victoria or El Palo, and get in the water during the hottest hours of the day. The sunsets in July are beautiful at least, and people are pretty friendly if you don't freak out about the heat.
What I'd recommend is don't do the classic thing of sitting in the sun at two in the afternoon like some clueless tourist. Rest at your hotel or go to museums with air conditioning after eating, go out again when it cools down a bit. The Alcázar, the Cathedral, all that stuff is there and it's interesting but you're better off doing it early in the morning. And if you want something more chill, the mountain towns nearby like Álora or Tolox have way more reasonable temperatures, they're half an hour by car away.
Personally I like April, May, or even October better, but not because Málaga is ugly in July but because you enjoy it more without sweating like you're in a sauna. Either way, lots of travelers go in July and have a great time, so don't give up. Just prepare yourself mentally for the heat and plan your schedule well.