Every couple is different, and the specific things that they wish they knew during their first year of marriage will depend on their individual circumstances and experiences. That being said, here are five things that many couples may wish they knew during their first year of marriage:

Communication is key: Being able to communicate openly, honestly, and effectively with your partner is essential to a healthy, happy marriage. It's important to make time to talk and listen to each other, and to be willing to compromise and work through any conflicts that may arise.
It's okay to ask for help: No one expects you to have all the answers or know how to handle every situation. It's okay to ask for help from friends, family, or professionals if you need it, whether it's for financial advice, relationship counseling, or practical support.
You will change and grow: Marriage is a journey, and both you and your partner will change and grow over time. It's important to be open to these changes and to support each other as you grow and evolve.
You will have ups and downs: Every marriage has its ups and downs, and it's normal to have conflicts and challenges. It's important to be patient, understanding, and willing to work through these challenges together.
It takes effort to keep the spark alive: Like any relationship, marriage requires effort to maintain the connection and keep the spark alive. Make time for each other, show appreciation and affection, and try new things together to keep the romance alive.

Remember, every marriage is different, and what works for one couple may not work for another. The most important thing is to be honest, open, and willing to communicate with your partner and work together to build a strong, healthy relationship.