Black Hole is incredibly dense object. So dense that weight of a cubic inch equals to the weight of Himalaya mountains. Yeah its 100% truth. A piece black hole which is 1 inch long wide and thick contains the same mass equals the Himalaya mountains.
A black hole is a region of space from which nothing, not even light, can escape. Around a black hole there is an undetectable surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass.
Light Year
A light-year is the distance that light travels in one year. Light year is unit to measure length (distance). It is not unit of time. A light year equals to 6 trillion miles (1013). It is tremendous distance. It is used to measure distance between stars and galaxies.
Cosmos
Originally cosmos is a Greek word. In today's terms cosmos is synonym to the word universe. It reflect the same meaning similar to universe.
Red Shift
Red shift in physical terms is said to happen, whenever an object move away from us. Reason for this is following. Red shift happened when light seen coming from an object is slightly increased in wave length. If wavelength of light coming from an object is decreased, it means object is coming towards us, and its color would be slightly blue. This is due to Doppler effect. Following video will tell you all, but you need to know the basic concepts of waves to understand. Watch it! hope you'll get it. Actually it is very interesting and very easy to follow video, so don't worry.
Habitable Zone
Habitable zone is the area around a star which is suitable to sustain life. A planet exists in habitable zone is very likely candidate to contain life on it. Habitable zone exists at a distance which is not too far away and not too close to a star. Closer planet would be hot, and it will no contain any water in liquid form. Further planets contain water in ice form.