In old Russian the verb "есть" had been used like it is used in English now, but in a more tricky way:
азъ есмь (I am);
ты еси (thou art);
он (она, оно) есть (he, she, it is);
мы есмы (we are);
вы есте (you are);
они суть (they are).
Then есмь, еси, есмы, есте had completely vanished but, probably, еси, which you may meet in the payer Отче наш иже еси на небеси (Father, who art in heven).
The forms есть and суть you may meet in some scientific works, prerending to be narrated in an old solemn style, like in geometry theorems - эти отрезки суть равны (these segments are equal) or этот треугольник есть равнобедренный, что и требовалось доказать (theis triangle is isocelos, what was being needed to demonstarte).
But some people do not understand the difference between есть and суть, and frequently make a mistake saying - Это не суть важно (it IS not important). The correct way is - Это не есть важно, because суть is for plural. Aanother meaning of the word суть in modern is "the essence". That may explain their making of the mistake.
In modern you may say Я есть человек (I am human), but it will bare a sense of old solemn or a jocular speaking. In realy morden language it is not used any more. But it is normal and welcome to use есть in the meaning of "to have", as it was explain in the comments above, like У меня есть ,балалайка (I have a balalayka). Mind, that у меня is in the dative case.
And here is a little bit of riddles. Try to understand and explain the meaning. The first one - У нас есть, что есть.
And one more from the poetry of Brodsky - Искусство есть искусство есть искусство...