50/50 vape juice is named this due to the ratio of PG (propylene glycol) and VG (vegetable glycerine). Vape liquid usually contains 4 main ingredients:
Nicotine, food-grade flavourings, PG & VG.
50/50 is a more universal and well known mix for vape liquid. The ratio of the juice you're vaping will depend on which kit, mod, or pen you have.
50/50 vape juice has an equal amount of PG VG and is a lot thinner than high VG liquid. Smaller kits with coils of 1 Ohm or more will utilise this liquid better than a sub-ohm coil. This means it's more suitable for vape pens and vape pods. Using a sub-ohm coil with thinner liquid will cause the liquid to burn too fast and burn the coil which could lead to a burnt taste. Because this liquid is recommended to use with a smaller kit, it's best vaped MTL (mouth to lung), where you inhale to your mouth first then to your lungs like a cigarette.
The higher the PG the more of a throat hit and flavour profile you'll receive, with less cloud vapour for a more discreet exhale. 50/50 is a balanced ratio that allows a medium throat hit, good flavour and average vapour production.
This 50/50 e-liquid is thinner and produces more of a throat hit. It's recommended to use a lower wattage on your device, anything 80 watts or below is usually a good choice. If you have a device that doesn't have customisable wattage then it should be designed to handle 50/50 liquids, whether its freebase or nic salt.
If you're just switching from smoking to vaping, it's more than likely you would've chose a starter kit or an all-in-one kit. These devices have a lower power than some of the big mod kits you may have seen. Because they produce less power, they produce less heat to the coil. Liquid needs to be thin enough to soak these coils throughout after each hit. If you have one of these devices and use a higher VG based liquid, it will be too thick for the coil and may not even vaporise, just gargle.