The 6ES7705-0AA00-1AA0 is a plug-in power supply unit for the SIMATIC S7 PG 70X programming device family, converting 230 V AC input to 24 V DC for the device's internal rail.
The 230 V AC input / 24 V DC output is sized specifically for the PG 70X programming device — it is not a general-purpose DIN-rail supply. If you are replacing a failed unit in an existing S7 programming station, this is the direct drop-in. For a new panel build, Siemens now recommends the current-generation SIMATIC power supply family, but the 6ES7705-0AA00-1AA0 remains the correct spare for the PG 70X.