How can I build a house that is only 5 meters wide by 25 meters long and have it still feel spacious?

i would like to have a like to consider having a small front & back yard plus car garage.

Is the property hemmed in on either side, or an end unit, or free-standing? If the garage is attached it may take up one of the yards, but maybe you can build a roof deck over it, or get it on a lower level. Built fewer rooms and design multi-use spaces that flow into one another. Provide long interior views; all the way through if possible.

If you are hemmed in, make the most of windows on the front - big and tall opening onto full-width rooms. Place smaller spaces like stairs, closets and baths in the center of the building. Consider skylights to bring light in the middle and see if some of that light can filter down into lower levels. Mirrors on side walls can make a room feel much more spacious, as will lighter colors. A lot of landscaping can happen in and enhance a very small space. Walling in the back yard to make it feel more private may help. Go up with a partial top floor that may have windows on both front and rear, or open to a private roof deck with long views.

If property is an end unit take advantage and put windows on the open side. Your dimensions do not prevent the house from being very nice - in some cities some of the best neighborhoods have fine houses no bigger. Provide desirable features, such as a space to take your boots off, even if only a small space is available for them.