Learn Russian: Это словарь. Он здесь.

Nouns ending in a soft sign (-ь) can be either masculine or feminine, so you often have to memorize their gender when you learn the word. Словарь is masculine. You can actually find a clue right in this sentence: the next sentence refers back to the dictionary using the masculine pronoun он.

Why does the second sentence use он (he) for a dictionary instead of a word for "it"?

In Russian, pronouns must match the grammatical gender of the noun they replace. Because словарь is a masculine noun, it is replaced by the masculine pronoun он, even though in English an inanimate object like a dictionary is always an "it".

Where is the word for "is" in Это словарь and Он здесь?

Russian completely drops the verb "to be" (am, is, are) in the present tense! You simply state the subject and what it equals side-by-side. So, Это словарь literally means "This [a] dictionary", and Он здесь means "He [is] here".

Both словарь and здесь end in a soft sign (ь). Does that change how they are pronounced?

Yes! The soft sign (ь) doesn't make a sound of its own, but it tells you to pronounce the consonant right before it "softly" (usually by raising the middle of your tongue toward the roof of your mouth, similar to the "y" sound in "yes"). This softens the р in словарь and the с in здесь.