Slated For Upgrades
You have to have completed the main quest "Locked Mementos" to unlock this side quest. Learn more about "Locked Mementos" here.
Slated For Upgrades will let you upgrade the powers of your Sheikah Slate, so it's highly recommended you do this as soon as you have obtained some Ancient materials, which can be scavenged from dead Guardians, will drop from live Guardians that you defeat, and are frequently found in chests all over Hyrule.
Talk to Purah and you can upgrade the following powers in your Sheikah Slate for the following materials.
Remote Bomb can be upgraded to Remote Bomb+ using three Ancient Shafts. The bomb cooldown time will drop dramatically and the bomb will now deal more damage.
Stasis can be upgraded to Stasis+ by giving Purah three Ancient Cores. The cooldown will drop and the time the object stays in Stasis will last longer. This is especially useful if you want to freeze bosses lik the Ganon Blights, for which regular Stasis is effectively useless.
Finally, you can upgrade your Sheikah Sensor, which you originally obtain from the Dueling Peaks Tower for Shrine detection. Give Purah three Ancient Screws. Now you can use your Hyrule Compedium and take your Sheikah Sensor to the next level.
Speak to Symin after upgrading the Sheikah Sensor for a sidequest teaching you the power of the new sensor.