In a recent updated posted on the offical website, we learnt that PUBG finally got its ping system, called Radio Messages. The messages are what you'd expect: Enemy Spotted, Affirmative, Negative, Thank You, Sorry, Need Med, Need Ammo and Need Backup:

Playing with players from different regions in random Duo or Squad matches or players with no access to voice chat have made it difficult to establish team-based strategy through close communication between team members. To help solve this problem, we are introducing text-based Radio Messages that will help you communicate with your team more quickly and easily for successful strategic gameplay.

• Hold the mouse wheel or F3 to open the Radio Message Wheel UI.
  • There are 8 types of messages provided–selected messages will be displayed on the left screen and immediately shown to your teammates.
  • Ping and Enemy Spotted, in particular, can be used in various circumstances. You can use them more quickly with separate key bindings.
    • Ping: Click the mouse wheel or press F3
    • Enemy Spotted: Double click the mouse wheel or double press F3
  • Pings has various interactions.
    • Select Ping near a certain item, and you can share the name and location of the pinged item with your teammates.
    • You can also use Ping on Care Packages or death crates to share their location.
    • Ping the direction you want to move toward to share the direction with your teammates.
    • All these features above automatically place a marker on the map and will be useful to utilize together with the Tactical Map Marker.
  • Enemy Spotted allows you to quickly share the location of an enemy you’ve spotted.
    • Use Enemy Spotted at the enemy’s location to mark it on the map and share it with your teammates.
    • Messages vary by distance:
      • Near Range: less than 50M
      • Medium Range: less than 200M
      • Long Range: 200M or more
      • Example: ENEMY SPOTTED! Long Range 300′
    • Ping and Enemy Spotted send messages to teammates within 500M.
  • Need Ammo works dynamically, with the message reflecting the ammo type of the weapon you are holding.
    • Example: If you select Need Ammo while holding an M416, the message sent to your teammates will be “I NEED 5.56mm.”
• You can mute Radio Messages from teammates individually in the Team Management menu.
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• Kill distance has been added to center-screen kill messages.
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• The distance between you and the enemy you killed will be displayed alongside the standard kill message in the middle of the screen.
  • Kill distance will only be shown you kill enemies from over 100 m away.
    • This will appear only when you kill the enemy by yourself.
  • DBNO kill messages remain the same and won’t show kill distance.

This is part of the Update #30 that's available on PC:

 

PUBG - Patch Report - PC Update #30