Yes, it can.
An AVA high-pressure washer is a product intended for outdoor use, and tested and approved with CE approval. This means that electrical components must be well protected against rain, and it must withstand being used outside even on a hot summer day in the scorching sun.
When it comes to storing the machine through the winter, things are of course a little different. The machine and accessories cannot withstand cold temperatures (less than around 2°C) unless properly and thoroughly prepared, and when any water inside the machine or accessories turns to ice it is likely to cause damage which can cause a lot of frustration.
Read more here about how you should secure the machine against frost damage before storage, and remember that most machines suffer frost damage in early autumn or late spring when the temperature drops overnight, not necessarily in the middle of winter in the shed.