What's wrong with this sign? Is it a grammatical or a mechanical problem? Both!

What are mechanics? Mechanics refers to the rules of the written language, such as capitalization, punctuation and spelling (Lethbridge College).

What's missing from this sign that makes it hard to understand?

Without the necessary period, the noun hunting (gerund) is easily mistaken for a verb (present participle), and the noun pedestrians becomes the direct object of hunting! Outdoor sports just became a lot more dangerous.

The second sign shows another example of how mechanics govern the brain's grammatical expectations. The way the sign reads, even though the fields are closed, no one will be punished for entering the field.

How is it that sign says the opposite of what it means? Missing its exclamation point, the noun trepassing (gerund) is mistaken for an adjective, describing violators.

Why does the brain do this? For an English-speaker, when one noun immediately follows another, the brain's tendency is to force the first noun into a role of descriptor, an adjective. So, the nouns farm and house, when one follows the other, develop a new relationship (adjective + noun): farm house.

Some uses of this relationship have become so regular that new, compound words have been formed:

street + light = streetlight

rail + road = railroad

home + work = homework (!)