Agfa Optima Ia (also marketed as Agfamatic Ia) is a 35mm viewfinder camera introduced in 1962. It was the 3rd in line of the Optima series, which are said to be the first "automatic" cameras.
The camera has a selenium cell light meter which generates voltage from light. This way it reads the lighting conditions and adjusts accordingly the shutter speed and the aperture. The shutter release lever has two levels. When you press and hold it half way, the camera reads the light. In the viewfinder you will see a red dot, which will turn green if the exposure is good. If so, you press the shutter release lever all the way to take the photo. If it stays red, it means that the scene is dark and you're going to need more light or a flash.
The only manual control you have over Optima Ia is when you set the mode ring to flash mode. This way you can choose your aperture, but the shutter speed will always be 1/30. You also have a "B" mode for long exposures, where you can also chose the aperture.
Focusing is done by a series of 3 symbols (portrait, group of people and landscape). There is no distance indication (apart from the close-up 1m - 3 1/4 ft), so your focus is done approximately. You can adjust the focus ring in between symbols, but generally the camera will use apertures that don't result in a very shallow depth of field, so you won't have a big problem with out of focus images.
The viewfinder front part, has a mirror surface which is very convenient for selfies (although not popular at the time), but you'll need to hold the camera far from your face (minimum distance with this lens is 1m). You can screw a close up lens for subjects closer than 1m. A cable release is also a good solution for selfies and also for long exposures using "B".
In general, it is a nice little camera, with not so many things to control and with a descent lens. The fact that it is made almost entirely from plastic (in contrast to other cameras of the Optima series) makes it feel a bit fragile and needs soft handling. A few things to keep in mind is that the selenium cells degrade over time and might not be able to measure the exposure properly. When not in use, you better keep the camera in its case or away from light, to extend the life of the selenium cells. Also, the ISO (ASA) settings go up to 250. Since the film's ISO is crucial for the camera to automatically choose the exposure settings, avoid using a film with higher ISO. If you do, your photos will be overexposed, unless you intend to use the camera in a darker environment.