The periodic table is like a big grid that is organized based on the atomic structure of the elements. The elements are placed in order based on their atomic numbers (the number of protons in their nuclei), starting in the upper left corner and read left to right/ top to bottom (like the sentences on a page).
There are also horizontal rows (periods) and vertical columns (families or groups) on the periodic table. The elements within the same period have electrons that are contained in similar energy levels (orbitals). For example, all of the elements in the top period have only one energy level, those in the second have two energy levels, etc.
Elements within the same vertical group have the same number of valence electrons (electrons found in the outermost energy level). These are the electrons that are involved in chemical bonds and determine an element's reactivity. Therefore, elements within the same group have similar reactivities.
The s, p, d and f blocks have to do with the orbital shape and orientations.
The periodic table can also be chunked into sections designating where metals, nonmetals, and metalloids are located.