"You can expect your first interest 6 months after the bonds are issued." What does this sentence mean for the Singapore Saving Bonds (SSB)?

That is correct. If you redeem your SSB before issuance of interest, your interest will be pro-rated and issued to you along with your capital during redemption. Once you have redeemed your SSB, redemption of SSB is done on 2nd business day of following month.​​​

I wouldn't recommend SSB at this point due to the low interest rate (<1%). Bank savings account and fixed desposit currently are offering better rates. Even if you have more than $75,000 (the amount insured for bank deposits), you can simply open up bank accounts with other banks.

Back to your question, it means that you are 'bidding' to buy the bond this month and successful applicants will be issued the bonds the following month. Interest on your bonds will be paid semi-annually (every 6 months).