Existencia y objetos de oficina
Expressing existence in Spanish is quite easy using the invariable verb hay, so no conjugation or agreement of the verb with the nouns are needed. For expressing non-existence it is as simple as adding no in front of the verb as in "no hay libros". Remember that the adverb no always precedes the verb, so phrases like "hay no libros" are totally wrong.
Other thing is deciding which articles to use in front of the noun, depending on the gender and number of objects, but also on whether we are expressing existence or non-existence. Connectives are also useful to make appropriate and more complex descriptions.
The following activities will help you to understand and learn all the mentioned issues as well as to revise the vocabulary.
ELE Actual A1 Lección 6
Aula internacional 1 Unidad 3