Complex sentence: It hosts the Southern African Large Telescope, the largest optical telescope in the southern hemisphere and is currently building the Karoo Array Telescope (or MeerKAT) as a pathfinder for the $20 billion Square Kilometer Array project.
Split into simpler sentences: It hosts the Southern African Large Telescope, the largest optical telescope in the southern hemisphere. South Africa is currently building the Karoo Array Telescope (or MeerKAT) as a pathfinder for the $20 billion Square Kilometer Array project.