STM32L053C8 discovery kit is best for ultra low power embedded application, featuring STM32L0 series MCU incorporating ARM Cortex M0+ core.
The STM32L053C8 discovery kit features the STM32L053C8T6 MCU with 64KB Flash memory and 8 Kbyte RAM in LQFP48 package. Therefore enables both advanced and beginners to make use of 2.04 E-paper display, Linear touch sensor and touch keys.
The STM32L053C8 board integrate an ST-Link debugger/programmer with a separate selection-mode switch which enables the board to be used as a standalone ST-LINK/V2-1. The board has three functionality USB support: Virtual COM port, mass storage, debug port. A separate USB-OTG is also provided for further debugging of the board.
STM32L0 discovery kit also expands the possibility for integrating other technology into the current version of the board via NFC connector for PLUG-CR95HF-B board. For easy software development, user can look for online tool with a support of Mbed online tools facility.Comprehensive free software including a variety of examples, part of STM32CubeL0 package.
Features:

STM32L053C8T6 microcontroller featuring 64 KB of Flash memory, 8 KB RAM in an LQFP48 package.
On-board ST-LINK/V2-1 with selection mode switch to use the kit as a standalone ST-LINK/V2-1 (with SWD connector for programming and debugging)
mbed-enabled (mbed.org)
USB ST-LINK with re-enumeration capability and three different interfaces:

virtual com port
mass storage
debug port

Board power supply: through USB bus or from an external 5 V supply voltage
External application power supply: 3 V and 5 V.
One linear touch sensor or four touchkeys.
IDD current measurement.
2.04 E-paper display, 172×72 pixels
Four LEDs:

LD1 (red/green) for USB communication
LD2 (red) for 3.3 V power-on
Two user LEDs: LD3 (green), LD4 (red)

Two pushbuttons (user and reset)
Extension header for LQFP48 I/Os for a quick connection to the prototyping board and easy probing
Comprehensive free software including a variety of examples, part of STM32CubeL0 package

Relevant Resoucres:
Discovery kit with STM32L0 series MCU
STM32L0 series Discovery Kit
FAQs:
Q: What is the main microcontroller used in this kit?
A: The STM32L0538-DISCO kit features the STM32L053C8T6 ultra-low-power microcontroller.
Q: What are the key features of this development kit?
A: The kit includes an embedded ST-LINK/V2-1 debugger, a 2.13″ E-paper display, a linear touch sensor or four touchkeys, and various LEDs and pushbuttons.
Q: Does this kit support Arduino?
A: While not directly Arduino-compatible, the STM32L0538-DISCO is supported by the STM32Cube ecosystem, which offers libraries and examples that simplify development.
Q: What connectivity options are available on the board?
A: The board features a USB Mini-B connector for programming and debugging, an NFC expansion connector, and flexible power supply options.
Q: What software and tools can I use with this kit?
A: The STM32L0538-DISCO is compatible with a wide range of Integrated Development Environments (IDEs), including IAR Embedded Workbench, MDK-ARM, and STM32CubeIDE. Comprehensive software libraries and examples are also available.