・・。
Many courses ban shoes with spikes, so be careful.
Literal
Shoes... spike-having things [object-を] ban courses [subject-が] many [because-ので], let's-be-careful.
A practical-tip sentence with a slightly halting delivery. The doubled period 「シューズ・・」 inserts a deliberate pause, as if the speaker is backing up to clarify — 'shoes, or rather, specifically spiked shoes.' スパイクのあるもの ('things that have spikes') uses the existential ある in a relative clause to modify もの ('things') with the quality of 'having spikes.' 気をつけましょう ('let's be careful') is the volitional form of 気をつける, used to give a cooperative warning — the ましょう makes it 'let's,' softening the caution into friendly advice. Common on warning signs and safety notices.