No, someone can't.
"Normal people" can not understand either Theory of Relativity, although any half intelligent person should know that there are two.
Sorry, stupidity has a price.
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We can explain a bit of it to you. The speed of light in a vacuum is only obtainable by light and other sub-atomic particles, such as gluons, that have no rest mass. For objects (and particles) with mass (rest mass), they can only approach the speed of light. If one object is moving at speed A and another is launched from the first object at speed B, our normal experience would have us conclude that the speed of the second object is A+B. Relativity shows us that this is not true. The actual speed is slightly less than that. As the speeds increase the difference between what we would calculate and reality grows, so that when an object traveling at 99% of the speed of light launches another object which travels at a speed, relative to the first, of 99% the speed of light, the combined speed is NOT 99% + 99% = 198% c; rather it is (roughly) 99.98%c. You can continue to launch objects, one from the other and at best will just get closer and closer to c, you will never reach that speed (except with light).
The speed of ANY object (which has rest mass) is relative to the coordinate system you chose. You can be correctly described as being at rest (with no velocity) and JUST as correctly described as traveling at 99.999%c, the choice is arbitrary. The choice should be made based on what frame of reference (coordinate system and origin) makes any calculations that are planned easiest to solve.
In order for the speed of light to be constant (in a vacuum), it is necessary that both space and time distort. We call space distortion, "length contraction" (or Lorentz contraction) and time distortion "time dilation".
Any object can be described to possess a "proper time". It is the time that a clock which accompanies the object (matching its speed and path) would record. The proper time (duration) between two events in our Universe (our Universe is a 4-dimensional space time) is:
proper duration = t√ [c² - (x²+y²+z²)/c²t²] where x,y and z are the distances in the 3 space directions traveled in time t (and of course, c is the speed of light in a vacuum). Examine this equation and you can see that the "proper duration" gets SMALLER as the distance traveled in a given time gets larger.
This means that a twin who travels to alpha centuri and back and comes back after 20 years will have aged LESS than the twin on Earth (because the traveling twin's proper time is less).
There are many other effects: as an object's speed increases, its apparent mass increases:
m = m°÷ √(1-(v/c)²) where v is the object's speed and m° is its rest mass. You can see from this equation that if v=c (which is impossible) then the denominator will be zero and the equation is not defined.
Gravity also distorts spacetime. The higher the gravity, the slower the proper time is relative to the time, t, of a stationary object. Remember that "stationary" is only relative to an arbitrarily chosen frame of reference (coordinate system).
Not only can mass not travel at c, but c is the maximum velocity that information can be transmitted.
The theory of General Relativity, which includes gravity, is only expressible using very advanced mathematics. Only the simplest problems can be exactly solved, most problems of interest can only be approximately solved and only by using computers.
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To the "normal" person, the only thing you need to know is that the GPS system would be off by about 50 ft a day if corrections for General and Special relativity were not made constantly. So, while it is Scientifically important, neither the birds in the sky, nor "normal" people need pay any attention to it. Bird brains are bird brains, after all.